# 1964 United States Senate elections

The 1964 United States Senate elections were held on November 3. The 33 seats of Class 1 were contested in regular elections. Special elections were also held to fill vacancies. They coincided with the election of President Lyndon B. Johnson by an overwhelming majority, to a full term. His Democratic Party picked up a net two seats from the Republicans. As of 2023, this was the last time either party has had a two-thirds majority in the Senate, which allowed the Senate Democrats to override a veto, propose constitutional amendments, or convict and expel certain officials without any votes from Senate Republicans. However, internal divisions would have prevented the Democrats from having done so. The Senate election cycle coincided with Democratic gains in the House in the same year.
In a close race in Nevada, Democratic incumbent Howard Cannon won re-election over Republican Lieutenant Governor Paul Laxalt by fewer than 100 votes. Laxalt joined Cannon in the Senate when he won Nevada's other seat in 1974. Patrick V. McNamara (D–Michigan) later died on April 30, 1966, and was replaced on May 11, 1966, by appointee Robert P. Griffin (R), reducing Democrats' majority to 67–33.
Notably, of the 35 seats up for election this year, 26 were held by Democrats, who managed to retain 25 of them. A party defending two-thirds of the seats up for election would not make net gains in the Senate again until 2012. Coincidentally, it would be the same Senate class, class 1.

## Results summary

| 68 | 32 |
| Democratic | Republican |
| Parties | Parties | | | | Total |
| Parties | Parties | Democratic | Republican | Other | Total |
| Last elections (1962) | Last elections (1962) | 67 | 33 | 0 | 100 |
| Before these elections | Before these elections | 66 | 34 | 0 | 100 |
| Not up | Not up | 40 | 25 | 0 | 65 |
| Up | Up | 26 | 9 | — | 35 |
| | Class 1 (1958→1964) | 24 | 9 | — | 33 |
| | Special: Class 2 | 2 | 0 | — | 2 |
| Incumbent retired | Incumbent retired | 1 | 1 | — | 2 |
| | Held by same party | 1 | 1 | — | 2 |
| | Replaced by other party | 0 | 0 | — | 0 |
| | Result | 1 | 1 | 0 | 2 |
| Incumbent ran | Incumbent ran | 25 | 8 | — | 33 |
| | Won re-election | 23 | 5 | — | 28 |
| | Lost re-election | 3 Republicans replaced by 3 Democrats 1 Democrat replaced by 1 Republican | 3 Republicans replaced by 3 Democrats 1 Democrat replaced by 1 Republican | — | 4 |
| | Lost renomination, but held by same party | 1 | 0 | — | 1 |
| | Result | 27 | 6 | 0 | 33 |
| Total elected | Total elected | 28 | 7 | 0 | 35 |
| Net gain/loss | Net gain/loss | 2 | 2 | | 2 |
| Nationwide vote | Nationwide vote | 30,786,035 | 23,171,991 | 848,082 | 54,806,108 |
| | Share | 56.17% | 42.28% | 1.55% | 100% |
| Result | Result | 68 | 32 | 0 | 100 |
Source:

## Gains, losses, and holds
### Retirements

One Republican did not seek re-election and one Democrat did not seek election to finish an unexpired term.
| State | Senator | Replaced by |
| Arizona | Barry Goldwater | Paul Fannin |
| Tennessee (special) | Herbert S. Walters | Ross Bass |

### Defeats

One Democrat sought election to finish the unexpired term but lost in the primary election. One Democrat sought election to a full term but lost in the general election. One Republican sought election to finish the unexpired term and sought election to a full term but lost in both the special election and the regular election. Two Republicans sought re-election but lost in the general election.
| State | Senator | Replaced by |
| California | Pierre Salinger | George Murphy |
| Maryland | J. Glenn Beall | Joseph Tydings |
| New Mexico | Edwin L. Mechem | Joseph Montoya |
| New York | Kenneth Keating | Robert F. Kennedy |
| Oklahoma | J. Howard Edmondson | Fred R. Harris |

### Post-election changes

One Democrat died on April 30, 1966, and was replaced on May 11, 1966, by a Republican appointee. Another Democrat died on April 18, 1965, and was replaced by a fellow Democrat. Another Democrat resigned on November 10, 1965, for health reasons and was replaced by a fellow Democrat.
| State | Senator | Replaced by |
| Michigan | Patrick V. McNamara | Robert P. Griffin |
| South Carolina | Olin D. Johnston | Donald S. Russell |
| Virginia | Harry F. Byrd | Harry F. Byrd Jr. |

## Change in composition
### Before the elections

| D$_1$ | D$_2$ | D$_3$ | D$_4$ | D$_5$ | D$_6$ | D$_7$ | D$_8$ | D$_9$ | D$_{10}$ |
| D$_{20}$ | D$_{19}$ | D$_{18}$ | D$_{17}$ | D$_{16}$ | D$_{15}$ | D$_{14}$ | D$_{13}$ | D$_{12}$ | D$_{11}$ |
| D$_{21}$ | D$_{22}$ | D$_{23}$ | D$_{24}$ | D$_{25}$ | D$_{26}$ | D$_{27}$ | D$_{28}$ | D$_{29}$ | D$_{30}$ |
| D$_{40}$ | D$_{39}$ | D$_{38}$ | D$_{37}$ | D$_{36}$ | D$_{35}$ | D$_{34}$ | D$_{33}$ | D$_{32}$ | D$_{31}$ |
| D$_{41}$ Calif. Ran | D$_{42}$ Conn. Ran | D$_{43}$ Fla. Ran | D$_{44}$ Ind. Ran | D$_{45}$ Maine Ran | D$_{46}$ Mass. Ran | D$_{47}$ Mich. Ran | D$_{48}$ Minn. Ran | D$_{49}$ Miss. Ran | D$_{50}$ Mo. Ran |
| Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | D$_{51}$ Mont. Ran |
| D$_{60}$ Texas Ran | D$_{59}$ Tenn. (sp) Retired | D$_{58}$ Tenn. (reg) Ran | D$_{57}$ R.I. Ran | D$_{56}$ Okla. (sp) Ran | D$_{55}$ Ohio Ran | D$_{54}$ N.D. Ran | D$_{53}$ N.J. Ran | D$_{52}$ Nev. Ran | D$_{51}$ Mont. Ran |
| D$_{61}$ Utah Ran | D$_{62}$ Va. Ran | D$_{63}$ Wash. Ran | D$_{64}$ W.Va. Ran | D$_{65}$ Wis. Ran | D$_{66}$ Wyo. Ran | R$_{34}$ Vt. Ran | R$_{33}$ Pa. Ran | R$_{32}$ N.Y. Ran | R$_{31}$ N.M. (sp) N.M. (reg) Ran |
| R$_{21}$ | R$_{22}$ | R$_{23}$ | R$_{24}$ | R$_{25}$ | R$_{26}$ Ariz. Retired | R$_{27}$ Del. Ran | R$_{28}$ Hawaii Ran | R$_{29}$ Md. Ran | R$_{30}$ Neb. Ran |
| R$_{20}$ | R$_{19}$ | R$_{18}$ | R$_{17}$ | R$_{16}$ | R$_{15}$ | R$_{14}$ | R$_{13}$ | R$_{12}$ | R$_{11}$ |
| R$_1$ | R$_2$ | R$_3$ | R$_4$ | R$_5$ | R$_6$ | R$_7$ | R$_8$ | R$_9$ | R$_{10}$ |

### Elections results

| D$_1$ | D$_2$ | D$_3$ | D$_4$ | D$_5$ | D$_6$ | D$_7$ | D$_8$ | D$_9$ | D$_{10}$ |
| D$_{20}$ | D$_{19}$ | D$_{18}$ | D$_{17}$ | D$_{16}$ | D$_{15}$ | D$_{14}$ | D$_{13}$ | D$_{12}$ | D$_{11}$ |
| D$_{21}$ | D$_{22}$ | D$_{23}$ | D$_{24}$ | D$_{25}$ | D$_{26}$ | D$_{27}$ | D$_{28}$ | D$_{29}$ | D$_{30}$ |
| D$_{40}$ | D$_{39}$ | D$_{38}$ | D$_{37}$ | D$_{36}$ | D$_{35}$ | D$_{34}$ | D$_{33}$ | D$_{32}$ | D$_{31}$ |
| D$_{41}$ Conn. Re-elected | D$_{42}$ Fla. Re-elected | D$_{43}$ Ind. Re-elected | D$_{44}$ Maine Re-elected | D$_{45}$ Mass. Re-elected | D$_{46}$ Mich. Re-elected | D$_{47}$ Minn. Re-elected | D$_{48}$ Miss. Re-elected | D$_{49}$ Mo. Re-elected | D$_{50}$ Mont. Re-elected |
| Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | Majority → | D$_{51}$ Nev. Re-elected |
| D$_{60}$ Utah Re-elected | D$_{59}$ Texas Re-elected | D$_{58}$ Tenn. (sp) Hold | D$_{57}$ Tenn. (reg) Re-elected | D$_{56}$ R.I. Re-elected | D$_{55}$ Okla. (sp) Hold | D$_{54}$ Ohio Re-elected | D$_{53}$ N.D. Re-elected | D$_{52}$ N.J. Re-elected | D$_{51}$ Nev. Re-elected |
| D$_{61}$ Va. Re-elected | D$_{62}$ Wash. Re-elected | D$_{63}$ W.Va. Re-elected | D$_{64}$ Wis. Re-elected | D$_{65}$ Wyo. Re-elected | D$_{66}$ Md. Gain | D$_{67}$ N.M. (sp) N.M. (reg) Gain | D$_{68}$ N.Y. Gain | R$_{32}$ Calif. Gain | R$_{31}$ Vt. Re-elected |
| R$_{21}$ | R$_{22}$ | R$_{23}$ | R$_{24}$ | R$_{25}$ | R$_{26}$ Ariz. Hold | R$_{27}$ Del. Re-elected | R$_{28}$ Hawaii Re-elected | R$_{29}$ Neb. Re-elected | R$_{30}$ Pa. Re-elected |
| R$_{20}$ | R$_{19}$ | R$_{18}$ | R$_{17}$ | R$_{16}$ | R$_{15}$ | R$_{14}$ | R$_{13}$ | R$_{12}$ | R$_{11}$ |
| R$_1$ | R$_2$ | R$_3$ | R$_4$ | R$_5$ | R$_6$ | R$_7$ | R$_8$ | R$_9$ | R$_{10}$ |
| Key | D$_#$ Democratic R$_#$ Republican |

## Race summary
### Special elections during the 88th Congress

In these special elections, the winner was seated during 1964 or before January 3, 1965; ordered by election date, then state.
| State | Incumbent | Incumbent | Incumbent | Results | Candidates |
| State | Senator | Party | Electoral history | Results | Candidates |
| New Mexico (Class 1) | Edwin L. Mechem | Republican | 1962 (Appointed) | Interim appointee lost election. New senator elected. Democratic gain. Winner also elected to the next term, see below. | ▌Y Joseph Montoya (Democratic) 54.7% ▌Edwin L. Mechem (Republican) 45.3% |
| Oklahoma (Class 2) | J. Howard Edmondson | Democratic | 1963 (Appointed) | Appointee lost nomination to finish term. New senator elected. Democratic hold. | ▌Y Fred R. Harris (Democratic) 51.2% ▌Bud Wilkinson (Republican) 48.8% |
| Tennessee (Class 2) | Herbert S. Walters | Democratic | 1963 (Appointed) | Appointee retired. New senator elected. Democratic hold. | ▌Y Ross Bass (Democratic) 52.1% ▌Howard Baker (Republican) 47.4% |

### Elections leading to the next Congress

In these general elections, the winners were elected for the term beginning January 3, 1965; ordered by state.
All of the elections involved the Class 1 seats.
| State | Incumbent | Incumbent | Incumbent | Results | Candidates |
| State | Senator | Party | Electoral history | Results | Candidates |
| Arizona | Barry Goldwater | Republican | 1952 1958 | Incumbent retired to run for President of the United States. New senator elected. Republican hold. | ▌Y Paul Fannin (Republican) 51.4% ▌Roy Elson (Democratic) 48.6% |
| California | Pierre Salinger | Democratic | 1964 (Appointed) | Interim appointee lost election. New senator elected. Republican gain. Incumbent resigned December 31, 1964, to give successor preferential seniority. Winner seated January 1, 1965. | ▌Y George Murphy (Republican) 51.5% ▌Pierre Salinger (Democratic) 48.5% |
| Connecticut | Thomas J. Dodd | Democratic | 1958 | Incumbent re-elected. | ▌Y Thomas J. Dodd (Democratic) 64.6% ▌John Davis Lodge (Republican) 35.3% |
| Delaware | John J. Williams | Republican | 1946 1952 1958 | Incumbent re-elected. | ▌Y John J. Williams (Republican) 51.7% ▌Elbert N. Carvel (Democratic) 48.3% ▌Hollon (Socialist Labor) 0.03% |
| Florida | Spessard Holland | Democratic | 1946 (Appointed) 1946 1952 1958 | Incumbent re-elected. | ▌Y Spessard Holland (Democratic) 63.9% ▌Claude R. Kirk Jr. (Republican) 36.0% |
| Hawaii | Hiram Fong | Republican | 1959 | Incumbent re-elected. | ▌Y Hiram Fong (Republican) 53.0% ▌Thomas Gill (Democratic) 46.4% ▌Lawrence Domine (Independent) 0.6% |
| Indiana | Vance Hartke | Democratic | 1958 | Incumbent re-elected. | ▌Y Vance Hartke (Democratic) 54.3% ▌D. Russell Bontrager (Republican) 45.3% Others ▌J. Ralston Miller (Prohibition) 0.3% ▌Casimer Kanczuzewski (Socialist Labor) 0.06% |
| Maine | Edmund Muskie | Democratic | 1958 | Incumbent re-elected. | ▌Y Edmund Muskie (Democratic) 66.6% ▌Clifford McIntire (Republican) 33.4% |
| Maryland | J. Glenn Beall | Republican | 1952 1958 | Incumbent lost re-election. New senator elected. Democratic gain. | ▌Y Joseph Tydings (Democratic) 62.8% ▌J. Glenn Beall (Republican) 37.2% |
| Massachusetts | Ted Kennedy | Democratic | 1962 (special) | Incumbent re-elected. | ▌Y Ted Kennedy (Democratic) 74.3% ▌Howard J. Whitmore Jr. (Republican) 25.4% Others ▌Lawrence Gilfedder (Socialist Labor) 0.2% ▌Grace F. Luder (Prohibition) 0.1% |
| Michigan | Philip Hart | Democratic | 1958 | Incumbent re-elected. | ▌Y Philip Hart (Democratic) 64.4% ▌Elly M. Peterson (Republican) 35.3% Others ▌Ernest C. Smith (Freedom Now) 0.1% ▌Evelyn Sell (Socialist Workers) 0.09% ▌James Sim (Socialist Labor) 0.05% |
| Minnesota | Eugene McCarthy | DFL | 1958 | Incumbent re-elected. | ▌Y Eugene McCarthy (DFL) 60.3% ▌Wheelock Whitney Jr. (Republican) 39.3% Others ▌William Braatz (Industrial Government) 0.3% ▌Everett E. Luoma (Socialist Workers) 0.1% |
| Mississippi | John C. Stennis | Democratic | 1947 (special) 1952 1958 | Incumbent re-elected. | ▌Y John C. Stennis (Democratic) Unopposed |
| Missouri | Stuart Symington | Democratic | 1952 1958 | Incumbent re-elected. | ▌Y Stuart Symington (Democratic) 66.6% ▌Jean P. Bradshaw (Republican) 33.4% |
| Montana | Mike Mansfield | Democratic | 1952 1958 | Incumbent re-elected. | ▌Y Mike Mansfield (Democratic) 64.5% ▌Alex Blewett (Republican) 35.5% |
| Nebraska | Roman Hruska | Republican | 1954 (special) 1958 | Incumbent re-elected. | ▌Y Roman Hruska (Republican) 61.4% ▌Raymond W. Arndt (Democratic) 38.6% |
| Nevada | Howard Cannon | Democratic | 1958 | Incumbent re-elected. | ▌Y Howard Cannon (Democratic) 50.0% ▌Paul Laxalt (Republican) 50.0% |
| New Jersey | Harrison A. Williams | Democratic | 1958 | Incumbent re-elected. | ▌Y Harrison A. Williams (Democratic) 61.9% ▌Bernard M. Shanley (Republican) 37.3% |
| New Mexico | Edwin L. Mechem | Republican | 1962 (Appointed) | Interim appointee lost election. New senator elected. Democratic gain. Winner was also elected to finish the term, see above. | ▌Y Joseph Montoya (Democratic) 54.7% ▌Edwin L. Mechem (Republican) 45.3% |
| New York | Kenneth Keating | Republican | 1958 | Incumbent lost re-election. New senator elected. Democratic gain. | ▌Y Robert F. Kennedy (Democratic) 53.5% ▌Kenneth Keating (Republican) 43.4% |
| North Dakota | Quentin Burdick | Democratic-NPL | 1960 (special) | Incumbent re-elected. | ▌Y Quentin Burdick (Democratic-NPL) 57.6% ▌Thomas S. Kleppe (Republican) 42.4% |
| Ohio | Stephen M. Young | Democratic | 1958 | Incumbent re-elected. | ▌Y Stephen M. Young (Democratic) 50.2% ▌Robert Taft Jr. (Republican) 49.8% |
| Pennsylvania | Hugh Scott | Republican | 1958 | Incumbent re-elected. | ▌Y Hugh Scott (Republican) 50.6% ▌Genevieve Blatt (Democratic) 49.1% |
| Rhode Island | John Pastore | Democratic | 1950 (special) 1952 1958 | Incumbent re-elected. | ▌Y John Pastore (Democratic) 82.7% ▌Ronald Rene Lagueux (Republican) 17.27% |
| Tennessee | Albert Gore Sr. | Democratic | 1952 1958 | Incumbent re-elected. | ▌Y Albert Gore Sr. (Democratic) 53.6% ▌Dan Kuykendall (Republican) 46.4% |
| Texas | Ralph Yarborough | Democratic | 1957 (special) 1958 | Incumbent re-elected. | ▌Y Ralph Yarborough (Democratic) 56.2% ▌George H. W. Bush (Republican) 43.6% |
| Utah | Frank Moss | Democratic | 1958 | Incumbent re-elected. | ▌Y Frank Moss (Democratic) 57.3% ▌Ernest L. Wilkinson (Republican) 42.7% |
| Vermont | Winston L. Prouty | Republican | 1958 | Incumbent re-elected. | ▌Y Winston L. Prouty (Republican) 53.5% ▌Frederick J. Fayette (Democratic) 46.5% |
| Virginia | Harry F. Byrd | Democratic | 1933 (Appointed) 1933 (special) 1934 1940 1946 1952 1958 | Incumbent re-elected. | ▌Y Harry F. Byrd (Democratic) 63.8% ▌Richard A. May (Republican) 19.0% ▌James W. Respess (Independent) 10.3% |
| Washington | Henry M. Jackson | Democratic | 1952 1958 | Incumbent re-elected. | ▌Y Henry M. Jackson (Democratic) 72.2% ▌Lloyd J. Andrews (Republican) 27.8% |
| West Virginia | Robert Byrd | Democratic | 1958 | Incumbent re-elected. | ▌Y Robert Byrd (Democratic) 67.7% ▌Cooper P. Benedict (Republican) 32.3% |
| Wisconsin | William Proxmire | Democratic | 1957 (special) 1958 | Incumbent re-elected. | ▌Y William Proxmire (Democratic) 53.3% ▌Wilbur N. Renk (Republican) 46.6% |
| Wyoming | Gale W. McGee | Democratic | 1958 | Incumbent re-elected. | ▌Y Gale W. McGee (Democratic) 54.0% ▌John S. Wold (Republican) 46.0% |

## Closest races

Fifteen races had a margin of victory under 10%:
| State | Party of winner | Margin |
| Nevada | Democratic | 0.04% |
| Ohio | Democratic | 0.4% |
| Pennsylvania | Republican | 1.5% |
| Oklahoma (special) | Democratic | 2.4% |
| Arizona | Republican | 2.8% |
| California | Republican (flip) | 3.4% |
| Delaware | Republican | 2.4% |
| Tennessee (special) | Democratic | 4.7% |
| Hawaii | Republican | 6.6% |
| Wisconsin | Democratic | 6.7% |
| Tennessee | Democratic | 7.2% |
| Vermont | Republican | 7.0% |
| Wyoming | Democratic | 8.0% |
| Indiana | Democratic | 9.0% |
| New Mexico | Democratic (flip) | 9.4% |
Michigan is the tipping point state with a margin of 29.1%.

## Arizona

Incumbent Barry Goldwater decided not to run for re-election to a third term, instead running for President of the United States as the Republican Party nominee against Lyndon B. Johnson. Governor of Arizona Paul Fannin ran unopposed in the Republican primary, and defeated Democratic nominee Roy Elson, who was a staff member for U.S. senator Carl Hayden until Hayden's retirement in 1969. Despite a landslide loss throughout the country, and Goldwater only able to obtain 50.45% of the vote in his home state of Arizona, Fannin managed to prevail in the state's Senate election. Goldwater would win the election for the other Senate seat in 1968 when Hayden retired from the post and serving two more terms.
Democratic primary results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Roy Elson | 76,697 | 41.41 |
| | Democratic | Renz L. Jennings | 64,331 | 34.73 |
| | Democratic | Howard V. Peterson | 22,424 | 12.11 |
| | Democratic | George Gavin | 10,291 | 5.56 |
| | Democratic | Raymond G. Neely | 6,022 | 3.25 |
| | Democratic | Robert P. Ketterer | 5,460 | 2.95 |
| Total votes | Total votes | Total votes | 185,225 | 100.00 |
1964 United States Senate election in Arizona :
| Party | Party | Candidate | Votes | % |
| | Republican | Paul Fannin | 241,089 | 51.43 |
| | Democratic | Roy Elson | 227,712 | 48.57 |
| Majority | Majority | Majority | 13,377 | 2.86 |
| Turnout | Turnout | Turnout | 468,801 | |
| | Republican hold | Republican hold | Republican hold | Republican hold |

## California

Democratic incumbent Pierre Salinger, who had been appointed to the seat following the death of Senator Clair Engle three months earlier, was defeated in his bid for a full term by Republican candidate George Murphy, a retired actor.
1964 United States Senate election in California :
| Party | Party | Candidate | Votes | % |
| | Republican | George Murphy | 3,628,552 | 51.54 |
| | Democratic | Pierre Salinger (Incumbent) | 3,411,915 | 48.46 |
| Majority | Majority | Majority | 216,537 | 3.08 |
| Turnout | Turnout | Turnout | 7,040,467 | |
| | Republican gain from Democratic | Republican gain from Democratic | Republican gain from Democratic | Republican gain from Democratic |

## Connecticut

Democrat Thomas J. Dodd was re-elected and served a second term. John Davis Lodge, grandson of Henry Cabot Lodge was defeated by almost 30%.
1964 United States Senate election in Connecticut :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Thomas J. Dodd (Incumbent) | 781,008 | 64.66 | |
| | Republican | John Davis Lodge | 426,939 | 35.34 | |
| Majority | Majority | Majority | 354,069 | 29.32 | |
| Turnout | Turnout | Turnout | 1,207,947 | | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Delaware

Republican incumbent John J. Williams was reelected to a fourth term, defeating Democratic Governor Elbert N. Carvel.
1964 United States Senate election in Delaware :
| Party | Party | Candidate | Votes | % |
| | Republican | John J. Williams (Incumbent) | 103,782 | 51.71 |
| | Democratic | Elbert N. Carvel | 96,850 | 48.26 |
| | Socialist Labor | Joseph B. Hollon Sr. | 71 | 0.04 |
| Majority | Majority | Majority | 6,932 | 3.45 |
| Turnout | Turnout | Turnout | 200,703 | |
| | Republican hold | Republican hold | Republican hold | Republican hold |

## Florida

Democratic incumbent Spessard Holland was reelected to a fourth term in a landslide, defeating the Republican candidate, future governor Claude R. Kirk Jr.
1964 United States Senate election in Florida :
| Party | Party | Candidate | Votes | % |
| | Democratic | Spessard L. Holland (Incumbent) | 997,585 | 63.93 |
| | Republican | Claude R. Kirk Jr. | 562,212 | 36.03 |
| | None | Scattering | 540 | 0.03 |
| Majority | Majority | Majority | 435,373 | 27.90 |
| Turnout | Turnout | Turnout | 1,560,337 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Hawaii

Republican incumbent Hiram Fong was reelected to a second term, defeating Democratic Congressman Thomas Gill
1964 United States Senate election in Hawaii :
| Party | Party | Candidate | Votes | % |
| | Republican | Hiram Fong (Incumbent) | 110,747 | 53.04 |
| | Democratic | Thomas P. Gill | 96,789 | 46.35 |
| | Independent | Lawrence Domine | 1,278 | 0.61 |
| Majority | Majority | Majority | 3,958 | 6.69 |
| Turnout | Turnout | Turnout | 208,814 | |
| | Republican hold | Republican hold | Republican hold | Republican hold |

## Indiana

Democratic incumbent Vance Hartke was reelected to a second term, defeating Republican State Senator Russell Bontrager.
1964 United States Senate election in Indiana :
| Party | Party | Candidate | Votes | % |
| | Democratic | Vance Hartke (Incumbent) | 1,128,505 | 54.33 |
| | Republican | D. Russell Bontrager | 941,519 | 45.33 |
| | Prohibition | J. Ralston Miller | 5,708 | 0.27 |
| | Socialist Labor | Casimer Kanczuzewski | 1,231 | 0.06 |
| Majority | Majority | Majority | 187,986 | 9.00 |
| Turnout | Turnout | Turnout | 2,076,963 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Maine

Democratic incumbent Edmund Muskie was reelected to a second term, defeating Republican Congressman Clifford McIntire in a landslide.
1964 United States Senate election in Maine :
| Party | Party | Candidate | Votes | % |
| | Democratic | Edmund S. Muskie (Incumbent) | 253,511 | 66.62 |
| | Republican | Clifford McIntire | 127,040 | 33.38 |
| Majority | Majority | Majority | 126,471 | 33.24 |
| Turnout | Turnout | Turnout | 380,551 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Maryland

Republican incumbent J. Glenn Beall was defeated in his bid for a third term by Democratic candidate Joseph Tydings, the former United States Attorney for the District of Maryland and son of former Senator Millard Tydings.
Beall's own son, J. Glenn Beall Jr., would go on to defeat Tydings six years later.
1964 United States Senate election in Maryland :
| Party | Party | Candidate | Votes | % |
| | Democratic | Joseph Tydings | 678,649 | 62.78 |
| | Republican | J. Glenn Beall (Incumbent) | 402,393 | 37.22 |
| | None | Write-Ins | 7 | 0.00 |
| Majority | Majority | Majority | 276,256 | 25.56 |
| Turnout | Turnout | Turnout | 1,081,049 | |
| | Democratic gain from Republican | Democratic gain from Republican | Democratic gain from Republican | Democratic gain from Republican |

## Massachusetts

Incumbent Democrat Ted Kennedy, who had won a special election two years earlier, defeated his challengers to win his second (his first full) Senate term. Much of the campaign-appearance burden on behalf of Ted Kennedy fell on his wife, Joan, because of Ted's serious back injury in a plane crash.
Candidates:
* Ted Kennedy - Incumbent senator elected in 1962 to the unexpired term of John F. Kennedy.
* Howard J. Whitmore Jr. - Member of Massachusetts House of Representatives from 1947 to 1953, and mayor of Newton, Massachusetts, from 1954 to 1960. Served in the United States Army Air Forces in World War II.
* Lawrence Gilfedder - Candidate for Lt. Governor in 1948. Ran for Governor in 1952 and 1954. Ran for Senate in 1958, 1960, 1962, 1964, 1966, and 1970.
* Grace F. Luder - Candidate for Massachusetts's 9th congressional district seat in 1950 and Massachusetts's 14th congressional district seat in 1952.
General election :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Edward M. Kennedy (Incumbent) | 1,716,907 | 74.26 | +21.3 |
| | Republican | Howard J. Whitmore Jr. | 587,663 | 25.42 | −19.08 |
| | Socialist Labor | Lawrence Gilfedder | 4,745 | 0.21 | −0.03 |
| | Prohibition | Grace F. Luder | 2,700 | 0.12 | +0.05 |
| Majority | Majority | Majority | 1,129,244 | 50.84 | |
| Turnout | Turnout | Turnout | 2,312,028 | | |
| | Democratic hold | Democratic hold | Swing | | |

## Michigan

Democratic incumbent Philip Hart was easily reelected to a second term over Republican challenger Elly M. Peterson.
1964 United States Senate election in Michigan :
| Party | Party | Candidate | Votes | % |
| | Democratic | Philip A. Hart (Incumbent) | 1,996,912 | 64.38 |
| | Republican | Elly M. Peterson | 1,096,272 | 35.34 |
| | Freedom Now | Ernest C. Smith | 4,125 | 0.13 |
| | Socialist Workers | Evelyn Sell | 2,754 | 0.09 |
| | Socialist Labor | James Sim | 1,598 | 0.05 |
| | None | Scattering | 6 | 0.00 |
| Majority | Majority | Majority | 90,640 | 29.04 |
| Turnout | Turnout | Turnout | 3,101,667 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Minnesota

Incumbent Democrat Eugene McCarthy defeated Republican challenger Wheelock Whitney Jr. to win a second term.
Democratic primary election results :
| Party | Candidate | Votes | % |
| Democratic (DFL) | Eugene McCarthy (Incumbent) | 245,068 | 90.47 |
| Democratic (DFL) | R. H. Underdahl | 14,562 | 5.38 |
| Democratic (DFL) | Joseph Nowak | 11,267 | 4.16 |
Republican primary election results :
| Party | Party | Candidate | Votes | % |
| | Republican | Wheelock Whitney Jr. | 161,363 | 100.00 |
General election results :
| Party | Party | Candidate | Votes | % |
| | Democratic (DFL) | Eugene McCarthy (Incumbent) | 931,363 | 60.34 |
| | Republican | Wheelock Whitney Jr. | 605,933 | 39.26 |
| | Industrial Government | William Braatz | 3,947 | 0.26 |
| | Socialist Workers | Everett E. Luoma | 2,357 | 0.15 |
| Majority | Majority | Majority | 325,420 | 21.09 |
| Turnout | Turnout | Turnout | 1,543,590 | |
| | Democratic (DFL) hold | Democratic (DFL) hold | Democratic (DFL) hold | Democratic (DFL) hold |

## Mississippi

Democratic incumbent John C. Stennis was reelected virtually unopposed to a fourth term, even as Republican candidate Barry Goldwater carried Mississippi in the presidential election. Stennis received 97% of the vote in the Democratic primary and faced no Republican challenger in the general election.
1964 United States Senate election in Mississippi :
| Party | Party | Candidate | Votes | % |
| | Democratic | John C. Stennis (Incumbent) | 343,364 | 100.00 |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Missouri

Democratic incumbent Stuart Symington was reelected to a third term in a landslide, defeating Republican candidate Jean Paul Bradshaw.
1964 United States Senate election in Missouri :
| Party | Party | Candidate | Votes | % |
| | Democratic | Stuart Symington (Incumbent) | 1,186,666 | 66.55 |
| | Republican | Jean Paul Bradshaw | 596,377 | 33.45 |
| Majority | Majority | Majority | 590,289 | 33.10 |
| Turnout | Turnout | Turnout | 1,783,043 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Montana

Incumbent Democrat Mike Mansfield, who was first elected to the Senate in 1952 and was re-elected in 1958, ran for re-election. Mansfield won the Democratic primary in a landslide, and advanced to the general election, where he faced Alex Blewett, the Majority Leader of the Montana House of Representatives and the Republican nominee. Though Mansfield's margin was significantly reduced from 1958, he still overwhelmingly defeated Blewett and won his third term in the Senate.
Democratic Party primary results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Mike Mansfield (Incumbent) | 109,904 | 85.51 |
| | Democratic | Joseph P. Monaghan | 18,630 | 14.49 |
| Total votes | Total votes | Total votes | 128,534 | 100.00 |
Republican Primary results :
| Party | Party | Candidate | Votes | % |
| | Republican | Alex Blewett | 31,934 | 59.37 |
| | Republican | Lyman Brewster | 12,375 | 23.01 |
| | Republican | Antoinette F. Rosell | 9,480 | 17.62 |
| Total votes | Total votes | Total votes | 53,789 | 100.00 |
1964 United States Senate election in Montana :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Mike Mansfield (Incumbent) | 180,643 | 64.51 | −11.71% |
| | Republican | Alex Blewett | 99,367 | 35.49 | +11.71% |
| Majority | Majority | Majority | 81,276 | 29.03 | −23.41% |
| Turnout | Turnout | Turnout | 280,010 | | |
| | Democratic hold | Democratic hold | Swing | | |

## Nebraska

Republican incumbent Roman Hruska was reelected in a landslide over Democratic challenger Raymond Arndt.
1964 United States Senate election in Nebraska :
| Party | Party | Candidate | Votes | % |
| | Republican | Roman L. Hruska (Incumbent) | 345,772 | 61.37 |
| | Democratic | Raymond W. Arndt | 217,605 | 38.62 |
| | None | Scattering | 24 | 0.00 |
| Majority | Majority | Majority | 128,167 | 22.75 |
| Turnout | Turnout | Turnout | 563,401 | |
| | Republican hold | Republican hold | Republican hold | Republican hold |

## Nevada

Incumbent Democratic U.S. Senator Howard Cannon won re-election to a second term by a razor-thin margin of only 48 votes over Republican Lieutenant Governor Paul Laxalt.
General election results :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Howard Cannon (Incumbent) | 67,336 | 50.02 | −7.66 |
| | Republican | Paul Laxalt | 67,288 | 49.98 | +7.66 |
| Majority | Majority | Majority | 48 | 0.04 | −15.32 |
| Turnout | Turnout | Turnout | 134,624 | | |
| | Democratic hold | Democratic hold | Swing | | |

## New Jersey

Democratic incumbent Harrison A. Williams was reelected to a second term over Republican candidate Bernard M. Shanley, a former white house staffer during the Eisenhower administration.
1964 United States Senate election in New Jersey :
| Party | Party | Candidate | Votes | % |
| | Democratic | Harrison A. Williams (Incumbent) | 1,677,515 | 61.91 |
| | Republican | Bernard M. Shanley | 1,011,280 | 37.32 |
| | Conservative | Harold P. Poeschel | 7,582 | 0.28 |
| | Socialist Workers | Lawrence Stewart | 6,147 | 0.23 |
| | America First | John Valgene Mahalchik | 4,926 | 0.18 |
| | Socialist Labor | Albert Ronis | 2,125 | 0.08 |
| Majority | Majority | Majority | 666,235 | 23.58 |
| Turnout | Turnout | Turnout | 2,709,575 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## New Mexico
### New Mexico (regular)

Incumbent Republican Edwin L. Mechem, who had been appointed to the seat following the death of Democrat Dennis Chávez two years earlier, sought election to a full term, but was defeated by Democrat Joseph Montoya.
Montoya was Lieutenant Governor of New Mexico (1947–1951 and 1955–1957) and a four-term member of the U.S. House of Representatives (1957–1964).
General election results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Joseph Montoya | 178,209 | 54.70 |
| | Republican | Edwin L. Mechem (Incumbent) | 147,562 | 45.30 |
| Majority | Majority | Majority | 30,647 | 9.41 |
| Total votes | Total votes | Total votes | 325,771 | 100.00 |
| | Democratic gain from Republican | Democratic gain from Republican | Democratic gain from Republican | Democratic gain from Republican |

### New Mexico (special)

Montoya was also elected to finish the term ending January 3, 1965.

## New York

Incumbent Republican U.S. Senator Kenneth Keating ran for re-election to a second term, but was defeated by Robert F. Kennedy, the former United States Attorney General and brother of former President John F. Kennedy and Massachusetts Senator Ted Kennedy.
The Socialist Labor state convention met on March 29, and nominated John Emanuel. The Republican state convention met on August 31, and re-nominated the incumbent U.S. Senator Kenneth B. Keating. The Conservative state convention met on August 31 at Saratoga Springs, New York, and nominated Prof. Henry Paolucci. The Democratic state convention met on September 1, and nominated U.S. Attorney General Robert F. Kennedy on the first ballot, with 968 votes against 153 for Congressman Samuel S. Stratton. The Liberal Party met on September 1, and endorsed the Democratic nominee, U.S. Attorney General Robert F. Kennedy. The Socialist Workers Party filed a petition to nominate candidates on September 7. Richard Garza was nominated.
John English, a Nassau County leader who helped John F. Kennedy during the 1960 presidential election, encouraged Robert Kennedy to oppose Keating. At the time, Samuel S. Stratton, a member of the United States House of Representatives from New York's 35th congressional district, was considered the most likely Democratic candidate. At first, Kennedy resisted. After President Kennedy's assassination, Robert Kennedy remained as Attorney General for Lyndon B. Johnson. However, Johnson and Kennedy feuded. Kennedy decided to run for the Senate in New York in August, and resigned from the Cabinet on September 3, 1964. While many reform Democrats resisted Kennedy, support from Robert F. Wagner Jr., and party bosses like Charles A. Buckley, of The Bronx, and Peter J. Crotty, of Buffalo, helped Kennedy win the nomination at the party convention.
During the campaign, Kennedy was frequently met by large crowds. Keating accused Kennedy of being a carpetbagger from Massachusetts. Kennedy responded to these charges in a televised town meeting by saying, "If the senator of the state of New York is going be selected on who's lived here the longest, then I think people are going vote for my opponent. If it's going be selected on who's got the best New York accent, then I think I'm probably out too. But I think if it's going be selected on the basis of who can make the best United States senator, I think I'm still in the contest."
The Democratic/Liberal candidate was elected. Campaign help from President Lyndon B. Johnson, as well as the Democratic landslide after the assassination of John F. Kennedy, helped carry Kennedy into office, as Kennedy polled about 1.1 million votes less in New York than Johnson did. The incumbent Keating was defeated.
1964 state election result :
| Ticket | U.S. Senator | U.S. Senator |
| Democratic | Y Robert F. Kennedy | 3,539,746 |
| Liberal | Y Robert F Kennedy | 284,646 |
| Republican | Kenneth B. Keating | 3,104,056 |
| Conservative | Henry Paolucci | 212,216 |
| Socialist Labor | John Emanuel | 7,358 |
| Socialist Workers | Richard Garza | 4,202 |
(For Total Votes, the Democratic and Liberal votes for Kennedy are combined.)

## North Dakota

Incumbent Democratic-NPL Senator Quentin Burdick sought and received re-election to his second term, defeating Republican candidate Thomas S. Kleppe, who later became the United States Secretary of the Interior.
Only Burdick filed as a Democratic-NPLer, and the endorsed Republican candidate was Thomas S. Kleppe, who would go on to serve two terms as a Representative for North Dakota's second congressional district from 1967 to 1971. Burdick and Kleppe won the primary elections for their respective parties.
1964 United States Senate election in North Dakota :
| Party | Party | Candidate | Votes | % |
| | Democratic–NPL | Quentin Burdick (Incumbent) | 149,264 | 57.64 |
| | Republican | Thomas S. Kleppe | 109,681 | 42.36 |
| Turnout | Turnout | Turnout | 219,560 | |

## Ohio

Democratic incumbent Stephen M. Young narrowly won reelection to a second term over Republican Congressman Robert Taft Jr., the son of former Senator Robert A. Taft and grandson of former President William Howard Taft.
Taft would go on to win the seat in the next election, serving one term in the Senate.
1964 United States Senate election in Ohio :
| Party | Party | Candidate | Votes | % |
| | Democratic | Stephen M. Young (Incumbent) | 1,923,608 | 50.22 |
| | Republican | Robert Taft Jr. | 1,906,781 | 49.78 |
| Majority | Majority | Majority | 16,827 | 0.44 |
| Turnout | Turnout | Turnout | 3,830,389 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Oklahoma (special)

This election was to determine who would serve for the final two years of the term to which Robert S. Kerr had been elected in 1960. Kerr had died in January 1963, and outgoing Governor J. Howard Edmondson was appointed to take his place. Edmondson hoped to win the special election, but lost the Democratic primary to former state senator Fred R. Harris, who then won the general election over University of Oklahoma football coach Bud Wilkinson.
1964 United States Senate special election in Oklahoma :
| Party | Party | Candidate | Votes | % |
| | Democratic | Fred R. Harris | 466,782 | 51.17 |
| | Republican | Bud Wilkinson | 445,392 | 48.83 |
| Majority | Majority | Majority | 21,390 | 3.34 |
| Turnout | Turnout | Turnout | 912,174 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Pennsylvania

Incumbent Republican U.S. Senator Hugh Scott successfully sought re-election to a second term, defeating Democratic nominee Genevieve Blatt.
General election results :
| Party | Party | Candidate | Votes | % | ±% |
| | Republican | Hugh Scott (Incumbent) | 2,429,858 | 50.59 | −0.62% |
| | Democratic | Genevieve Blatt, Pennsylvania Secretary of Internal Affairs | 2,359,223 | 49.12 | +0.74% |
| | Socialist Workers | Morris Chertov | 7,317 | 0.15 | +0.01% |
| | Socialist Labor | George S. Taylor | 6,881 | 0.14 | −0.12% |
| | N/A | Other | 473 | 0.00 | N/A |
| Majority | Majority | Majority | 70,635 | 1.47 | |
| Turnout | Turnout | Turnout | 4,803,752 | | |
| | Republican hold | Republican hold | Swing | | |

## Rhode Island

Democratic incumbent John Pastore won reelection to a third full term (and fourth overall), defeating Republican candidate Ronald Lagueux by more than 65 percentage points.
1964 United States Senate election in Rhode Island :
| Party | Party | Candidate | Votes | % |
| | Democratic | John Pastore (Incumbent) | 319,607 | 82.73 |
| | Republican | Ronald Legueux | 66,715 | 17.27 |
| Majority | Majority | Majority | 252,892 | 65.45 |
| Turnout | Turnout | Turnout | 386,322 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Tennessee
### Tennessee (regular)

Incumbent Democrat Albert Gore Sr. was re-elected to a third term over Republican candidate Dan Kuykendall.
General election results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Albert Gore Sr. (incumbent) | 570,542 | 53.62 |
| | Republican | Dan Kuykendall | 493,475 | 46.38 |
| Majority | Majority | Majority | 77,067 | 7.24 |
| Turnout | Turnout | Turnout | 1,064,017 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

### Tennessee (special)

Democratic Congressman Ross Bass won the special election to serve the remaining 26 months of the term to which the late Estes Kefauver had been elected in 1960. He defeated Republican candidate Howard Baker, who would go on to win the seat in the regular election two years later.
General election results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Ross Bass | 568,905 | 52.14 |
| | Republican | Howard Baker | 517,330 | 47.41 |
| | Independent | Melvin Babcock Morgan | 4,853 | 0.44 |
| Majority | Majority | Majority | 51,575 | 4.73 |
| Turnout | Turnout | Turnout | 1,091,088 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Texas

Incumbent Democrat Ralph Yarborough defeated future President of the United States George H. W. Bush.
Although Yarborough won this election, he would lose the Democratic Primary six years later, in 1970, to Lloyd Bentsen. Bush later went on to win an election for the United States House of Representatives in 1966; he was elected vice president of the United States in 1980 and was elected president in 1988.
1964 United States Senate election in Texas :
| Party | Party | Candidate | Votes | % |
| | Democratic | Ralph W. Yarborough (Incumbent) | 1,463,958 | 56.22 |
| | Republican | George H. W. Bush | 1,134,337 | 43.56 |
| | Constitution | Jack Carswell | 5,542 | 0.21 |
| Majority | Majority | Majority | 329,621 | 12.66 |
| Turnout | Turnout | Turnout | 2,603,837 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Utah

Democratic incumbent Frank Moss was reelected to a second term over Republican candidate Ernest L. Wilkinson, the president of Brigham Young University.
1964 United States Senate election in Utah :
| Party | Party | Candidate | Votes | % |
| | Democratic | Frank Moss (Incumbent) | 227,822 | 57.33 |
| | Republican | Ernest L. Wilkinson | 169,562 | 42.67 |
| Majority | Majority | Majority | 58,260 | 14.66 |
| Turnout | Turnout | Turnout | 397,384 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Vermont

Incumbent Republican Winston L. Prouty successfully ran for re-election, defeating Democratic candidate Frederick J. Fayette.
Republican primary results :
| Party | Party | Candidate | Votes | % |
| | Republican | Winston L. Prouty (Incumbent) | 43,648 | 99.9 |
| | Republican | Other | 63 | 0.1 |
| Total votes | Total votes | Total votes | '43,711' | '100' |
Democratic primary results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Frederick J. Fayette | 12,388 | 71.1 |
| | Democratic | William H. Meyer | 4,913 | 28.2 |
| | Democratic | Other | 134 | 0.7 |
| Total votes | Total votes | Total votes | '17,435' | '100' |
1964 United States Senate election in Vermont :
| Party | Party | Candidate | Votes | % |
| | Republican | Winston L. Prouty | 83,302 | 50.7 |
| | Independent | Winston L. Prouty | 4,516 | 2.7 |
| | Write-in | Winston L. Prouty | 61 | 0.0 |
| | Republican + Independent + Write-in | Winston L. Prouty (Incumbent) | 87,879 | 53.4 |
| | Democratic | Frederick J. Fayette | 76,457 | 46.5 |
| | N/A | Other | 14 | 0.0 |
| Majority | Majority | Majority | 11,422 | 6.95 |
| Total votes | Total votes | Total votes | '164,350' | '100.00%' |
| | Republican hold | Republican hold | Swing | |

## Virginia

Incumbent Harry F. Byrd was re-elected to a seventh term, defeating Republican Richard A. May and independent James W. Respess.
1964 United States Senate election in Virginia :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Harry F. Byrd (Incumbent) | 592,270 | 63.80 | −5.52% |
| | Republican | Richard A. May | 176,624 | 19.03 | +19.03% |
| | Independent | James W. Respess | 95,526 | 10.29 | |
| | Independent | J.B. Brayman | 30,594 | 3.30 | |
| | Independent | Milton L. Green | 12,110 | 1.30 | |
| | Independent | Robert E. Poole Jr. | 10,774 | 1.16 | |
| | Independent | Willie T. Wright | 10,424 | 1.12 | |
| | Write-ins | | 51 | 0.01 | |
| Majority | Majority | Majority | 415,646 | 44.77 | +1.72% |
| Turnout | Turnout | Turnout | 928,373 | | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Washington

Democratic incumbent Henry M. Jackson was reelected to a third term in a landslide, defeating Republican challenger Lloyd J. Andrews, who had previously served as the state's Superintendent of Public Instruction.
1964 United States Senate election in Washington :
| Party | Party | Candidate | Votes | % |
| | Democratic | Henry M. Jackson (Incumbent) | 875,950 | 72.21 |
| | Republican | Lloyd J. Andrews | 337,138 | 27.79 |
| Majority | Majority | Majority | 538,812 | 44.42 |
| Turnout | Turnout | Turnout | 1,213,088 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## West Virginia

Democratic incumbent Robert Byrd was reelected to a second term over Republican candidate Cooper Benedict. Byrd would serve in the Senate until his death in 2010, making him the longest-serving senator in United States history.
1964 United States Senate election in West Virginia :
| Party | Party | Candidate | Votes | % |
| | Democratic | Robert Byrd (Incumbent) | 515,015 | 67.67 |
| | Republican | Cooper P. Benedict | 246,072 | 32.33 |
| Majority | Majority | Majority | 268,943 | 34.33 |
| Turnout | Turnout | Turnout | 761,087 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Wisconsin

Incumbent Democrat William Proxmire was reelected to a second full term, defeating Republican Wilbur Renk.
1964 United States Senate election in Wisconsin :
| Party | Party | Candidate | Votes | % |
| | Democratic | William Proxmire (Incumbent) | 892,013 | 53.29 |
| | Republican | Wilbur N. Renk | 780,116 | 46.61 |
| | Independent | Kenneth F. Klinkerk | 1,062 | 0.06 |
| | Independent | Wayne Leverenz | 479 | 0.03 |
| | None | Scattering | 106 | 0.01 |
| Majority | Majority | Majority | 111,897 | 6.68 |
| Turnout | Turnout | Turnout | 1,673,776 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

## Wyoming

1964 United States Senate election in Wyoming :
| Party | Party | Candidate | Votes | % |
| | Democratic | Gale McGee (Incumbent) | 76,485 | 53.99 |
| | Republican | John S. Wold | 65,185 | 46.01 |
| Majority | Majority | Majority | 11,300 | 6.98 |
| Turnout | Turnout | Turnout | 141,670 | |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold |