# 2018 United States Senate election in Montana

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vte :
The 2018 United States Senate election in Montana was held on November 6, 2018, to elect a member of the United States Senate to represent the State of Montana, concurrently with other elections to the United States Senate, elections to the United States House of Representatives and various state and local elections.
This was one of ten Democratic-held Senate seats up for election in a state that Donald Trump won in the 2016 presidential election. Incumbent Democratic Senator Jon Tester was reelected to a third term, defeating Republican State Auditor Matt Rosendale. Rosendale conceded on November 7, 2018. This was the first Senate election in which Tester received a majority of votes cast rather than a simple plurality. As of 2025, this is the last time Democrats won any congressional and/or statewide election in Montana.
Following his loss, Rosendale went on to run for Montana's vacant congressional seat in 2020 and won, taking office in the U.S. House of Representatives in January 2021.

## Democratic primary
### Candidates
#### Nominated

* Jon Tester, incumbent U.S. senator

### Endorsements
#### U.S. executive branch officials

* Joe Biden, 47th vice president of the United States

#### U.S. senators

* Dick Durbin, U.S. senator (IL) and Senate Minority Whip
* Al Franken, former U.S. senator (MN)
* Kamala Harris, U.S. senator (CA)
* Amy Klobuchar, U.S. senator (MN)
* Ed Markey, U.S. senator (MA)
* Tom Udall, U.S. senator (NM)
* Elizabeth Warren, U.S. senator (MA)

#### Local and statewide politicians

* Steve Bullock, governor of Montana

#### Organizations

* Council for a Livable World
* End Citizens United
* League of Conservation Voters Action Fund
* NARAL Pro-Choice America

### Results

Democratic primary results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Jon Tester (incumbent) | 114,948 | 100.00% |
| Total votes | Total votes | Total votes | 114,948 | 100.00% |

## Republican primary
### Candidates
#### Nominated

* Matt Rosendale, auditor of Montana and candidate for Congress in 2014

#### Eliminated in primary

* Troy Downing, veteran and businessman
* Russell Fagg, former Yellowstone County District Judge
* Albert Olszewski, state senator and candidate for lieutenant governor in 2012

#### Withdrew

* Ron Murray, businessman and candidate for the state house in 2010

#### Declined

* Tim Fox, Attorney General of Montana
* Robert J. O'Neill, former Navy SEAL (endorsed Troy Downing)
* Marc Racicot, former governor and former chairman of the Republican National Committee (endorsed Russell Fagg)
* Corey Stapleton, Secretary of State of Montana, candidate for governor in 2012 and candidate for Congress in 2014
* Ryan Zinke, former Secretary of the Interior and former U.S. representative

### Endorsements
#### U.S. executive branch officials

* Donald Trump

#### U.S. senators

* Ted Cruz (TX)
* Mike Lee (UT)

#### Individuals

* Steve Bannon, former White House Chief Strategist and executive chair of Breitbart News

#### Organizations

* CatholicVote.org
* Citizens United Political Victory Fund
* Club for Growth
* FreedomWorks
* Great America Alliance
* Senate Conservatives Fund

### Polling

| Poll source | Date(s) administered | Sample size | Margin of error | Troy Downing | Russell Fagg | Al Olszewski | Matt Rosendale | Other | Undecided |
| WPA Intelligence (R-Club for Growth) | April 15–16, 2018 | 503 | ± 4.4% | 12% | 17% | 8% | 40% | – | 23% |
| WPA Intelligence (R-Rosendale) | February 5–7, 2018 | 401 | ± 4.4% | 12% | 11% | 5% | 28% | 1% | – |

### Results

Republican primary results :
| Party | Party | Candidate | Votes | % |
| | Republican | Matt Rosendale | 51,859 | 33.82% |
| | Republican | Russ Fagg | 43,465 | 28.34% |
| | Republican | Troy Downing | 29,341 | 19.13% |
| | Republican | Al Olszewski | 28,681 | 18.70% |
| Total votes | Total votes | Total votes | 153,346 | 100.00% |

## Libertarian primary
### Candidates
#### Nominated

* Rick Breckenridge, 2016 candidate for the U.S. House of Representatives
In October 2018, Breckenridge told a reporter from the Associated Press that he opposed the use of dark money in politics. Breckenridge said that he realistically anticipated only receiving three or four percent of the vote in the general election, and that he endorsed Rosendale's efforts to stop the use of dark money in politics. The Associated Press interpreted Breckenridge's comments as a statement that Breckenridge was dropping out of the race and endorsing Rosendale. Breckenridge later stated that his use of the word "endorse" referred only to stopping the use of dark money in politics, and said he was still running for the Senate.

## Green Party

Kelly won the Green Party nomination, but a Montana district court judge ruled that he had insufficient signatures to get on the ballot.

### Candidates
#### Nominee (removed from ballot)

* Steve Kelly, artist and environmental activist

#### Eliminated in primary

* Timothy Adams

### Results

Green primary results :
| Party | Party | Candidate | Votes | % |
| | Green | Steve Kelly | 971 | 61.22% |
| | Green | Timothy Adams | 615 | 38.78% |
| Total votes | Total votes | Total votes | 1,586 | 100% |

## General election
### Debates

* Complete video of debate, C-SPAN September 29, 2018
* Complete video of debate, YouTube October 14, 2018

### Predictions

| Source | Ranking | As of |
| The Cook Political Report | Tossup | October 26, 2018 |
| Inside Elections | Tilt D | November 1, 2018 |
| Sabato's Crystal Ball | Lean D | November 5, 2018 |
| Daily Kos | Tossup | November 1, 2018 |
| Fox News | Lean D | November 1, 2018 |
| CNN | Lean D | November 1, 2018 |
| RealClearPolitics | Tossup | November 5, 2018 |
| FiveThirtyEight | Likely D | November 6, 2018 |

### Endorsements
#### U.S. executive branch officials

* Joe Biden, 47th vice president of the United States

#### U.S. senators

* Dick Durbin, U.S. senator (IL) and Senate Minority Whip
* Al Franken, former U.S. senator (MN)
* Kamala Harris, U.S. senator (CA)
* Amy Klobuchar, U.S. senator (MN)
* Ed Markey, U.S. senator (MA)
* Tom Udall, U.S. senator (NM)
* Elizabeth Warren, U.S. senator (MA)

#### Newspapers

* Billings Gazette
* Missoulian

#### Local and statewide politicians

* Steve Bullock, governor of Montana

#### Organizations

* Communications Workers of America
* Council for a Livable World
* End Citizens United
* Feminist Majority Political Action Committee
* League of Conservation Voters Action Fund
* NARAL Pro-Choice America
* National Committee to Preserve Social Security and Medicare
* National Education Association
* National Wildlife Federation Action Fund
* Population Connection

#### U.S. executive branch officials

* Mike Pence, 48th vice president of the United States
* Donald Trump, 45th president of the United States

#### U.S. senators

* Ted Cruz (TX)
* Steve Daines (MT)
* Cory Gardner (CO)
* Mike Lee (UT)
* Rand Paul (KY)

#### U.S. representatives

* Greg Gianforte (MT-AL)

#### Individuals

* Steve Bannon, former White House Chief Strategist and executive chair of Breitbart News
* Rick Breckenridge, former Libertarian nominee in this election
* Troy Downing, veteran and 2018 Senate challenger
* Alvin "A.J." Not Afraid, chairman of the Crow Tribe

#### Organizations

* Americans for Prosperity
* CatholicVote.org
* Citizens United Political Victory Fund
* Club for Growth
* FreedomWorks
* Great America Alliance
* Montana Shooting Sports Association
* National Organization for Marriage
* National Right to Life
* NRA Political Victory Fund
* Senate Conservatives Fund
* Tea Party Express
* U.S. Chamber of Commerce

### Fundraising

Campaign finance reports as of October 17, 2018 :
| Candidate (party) | Total receipts | Total disbursements | Cash on hand |
| Jon Tester (D) | $19,499,290 | $17,946,600 | $1,612,530 |
| Matt Rosendale (R) | $5,034,075 | $4,515,910 | $524,379 |
| Rick Breckenridge (L) | - | - | - |
| Source: Federal Election Commission ||||

### Polling

| Poll source | Date(s) administered | Sample size | Margin of error | Jon Tester (D) | Matt Rosendale (R) | Rick Breckenridge (L) | Other | Undecided |
| The Trafalgar Group (R) | November 2–5, 2018 | 953 | ± 3.2% | 50% | 49% | – | 1% | 0% |
| HarrisX | November 1–5, 2018 | 500 | ± 4.4% | 50% | 42% | – | – | – |
| Change Research | November 2–4, 2018 | 879 | – | 46% | 49% | 3% | – | – |
| HarrisX | October 31 – November 4, 2018 | 500 | ± 4.4% | 49% | 43% | – | – | – |
| HarrisX | October 30 – November 3, 2018 | 500 | ± 4.4% | 49% | 43% | – | – | – |
| HarrisX | October 29 – November 2, 2018 | 500 | ± 4.4% | 50% | 42% | – | – | – |
| HarrisX | October 28 – November 1, 2018 | 500 | ± 4.4% | 49% | 42% | – | – | – |
| HarrisX | October 27–31, 2018 | 500 | ± 4.4% | 49% | 42% | – | – | – |
| HarrisX | October 24–30, 2018 | 700 | ± 3.7% | 48% | 40% | – | – | – |
| Gravis Marketing | October 24–26, 2018 | 782 | ± 3.5% | 48% | 45% | – | – | 7% |
| University of Montana | October 10–18, 2018 | 533 | ± 4.3% | 49% | 39% | 2% | – | 10% |
| Montana State University Billings | October 8–13, 2018 | 471 | ± 4.5% | 47% | 38% | 3% | – | 12% |
| Montana State University Bozeman | September 15 – October 6, 2018 | 2,079 | ± 2.2% | 46% | 43% | 3% | 2% | 7% |
| Public Policy Polling (D-Protect Our Care) | September 28, 2018 | 594 | ± 4.0% | 49% | 45% | – | – | 6% |
| Gravis Marketing | September 19–22, 2018 | 710 | ± 3.7% | 49% | 45% | – | – | 6% |
| Axis Research (R-NRSC) | September 17–19, 2018 | – | ± 4.5% | 44% | 44% | 4% | – | 8% |
| AARP/Benenson Strategy Group (D) | September 6–16, 2018 | 950 | ± 3.1% | 50% | 43% | – | 2% | 5% |
| CBS News/YouGov | September 10–14, 2018 | 453 | – | 47% | 45% | – | 3% | 5% |
| University of Montana | August 13–31, 2018 | 466 | ± 4.5% | 56% | 32% | 2% | – | 9% |
| WPA Intelligence (R-NRSC) | August 20–22, 2018 | 600 | ± 4.0% | 45% | 47% | – | – | 5% |
| Remington Research (R) | July 8–10, 2018 | 2,581 | ± 2.0% | 49% | 46% | – | – | 5% |
| SurveyMonkey/Axios | June 11 – July 2, 2018 | 974 | ± 5.0% | 55% | 43% | – | – | 3% |
| Gravis Marketing | June 11–13, 2018 | 469 | ± 4.5% | 52% | 44% | – | – | 4% |
| Poll source | Date(s) administered | Sample size | Margin of error | Jon Tester (D) | Generic Republican | Undecided |
| SurveyMonkey/Axios | February 12–March 5, 2018 | 1,484 | ± 3.4% | 42% | 55% | 3% |

### Results

United States Senate election in Montana, 2018 :
| Party | Party | Candidate | Votes | % | ±% |
| | Democratic | Jon Tester (incumbent) | 253,876 | 50.33% | +1.75% |
| | Republican | Matt Rosendale | 235,963 | 46.78% | +1.92% |
| | Libertarian | Rick Breckenridge | 14,545 | 2.88% | −3.68% |
| Total votes | Total votes | Total votes | 504,384 | 100.00% | N/A |
| | Democratic hold | Democratic hold | Democratic hold | Democratic hold | Democratic hold |

#### By county

From Secretary of State of Montana
| County | Jon Tester Democratic | Jon Tester Democratic | Matt Rosendale Republican | Matt Rosendale Republican | Rick Breckenridge Libertarian | Rick Breckenridge Libertarian | Total Votes |
| County | # | % | # | % | # | % | Total Votes |
| Beaverhead | 1,876 | 38.31% | 2,866 | 58.53% | 155 | 3.17% | 4,897 |
| Big Horn | 3,027 | 64.73% | 1,558 | 33.32% | 91 | 1.95% | 4,676 |
| Blaine | 1,961 | 64.96% | 982 | 32.53% | 76 | 2.52% | 3,019 |
| Broadwater | 1,071 | 32.84% | 2,086 | 63.97% | 104 | 3.19% | 3,261 |
| Carbon | 2,680 | 44.17% | 3,209 | 52.89% | 178 | 2.93% | 6,067 |
| Carter | 128 | 17.02% | 602 | 80.05% | 22 | 2.93% | 752 |
| Cascade | 17,435 | 51.27% | 15,566 | 45.77% | 1,008 | 2.96% | 34,009 |
| Chouteau | 1,275 | 47.99% | 1,312 | 49.38% | 70 | 2.63% | 2,657 |
| Custer | 1,942 | 39.77% | 2,762 | 56.56% | 179 | 3.67% | 4,883 |
| Daniels | 281 | 29.86% | 631 | 67.06% | 29 | 3.08% | 941 |
| Dawson | 1,233 | 30.27% | 2,700 | 66.29% | 140 | 3.44% | 4,073 |
| Deer Lodge | 2,892 | 68.27% | 1,208 | 28.52% | 136 | 3.21% | 4,236 |
| Fallon | 281 | 21.80% | 951 | 73.78% | 57 | 4.42% | 1,289 |
| Fergus | 1,964 | 33.90% | 3,640 | 62.83% | 189 | 3.26% | 5,793 |
| Flathead | 19,652 | 41.15% | 26,759 | 56.03% | 1,349 | 2.82% | 47,760 |
| Gallatin | 33,251 | 59.45% | 21,248 | 37.99% | 1,434 | 2.56% | 55,933 |
| Garfield | 81 | 11.88% | 571 | 83.72% | 30 | 4.40% | 682 |
| Glacier | 3,754 | 75.14% | 1,153 | 23.08% | 89 | 1.78% | 4,996 |
| Golden Valley | 130 | 28.63% | 303 | 66.74% | 21 | 4.63% | 454 |
| Granite | 695 | 38.76% | 1,046 | 58.34% | 52 | 2.90% | 1,793 |
| Hill | 3,729 | 58.36% | 2,434 | 38.09% | 227 | 3.55% | 6,390 |
| Jefferson | 2,954 | 43.23% | 3,653 | 53.46% | 226 | 3.31% | 6,833 |
| Judith Basin | 388 | 32.58% | 752 | 63.14% | 51 | 4.28% | 1,191 |
| Lake | 6,916 | 50.22% | 6,491 | 47.13% | 365 | 2.65% | 13,772 |
| Lewis and Clark | 20,506 | 57.70% | 14,106 | 39.69% | 927 | 2.61% | 35,539 |
| Liberty | 365 | 37.21% | 586 | 59.73% | 30 | 3.06% | 981 |
| Lincoln | 2,902 | 31.08% | 6,137 | 65.73% | 298 | 3.19% | 9,337 |
| Madison | 1,890 | 38.11% | 2,898 | 58.44% | 171 | 3.45% | 4,959 |
| McCone | 227 | 22.06% | 773 | 75.12% | 29 | 2.82% | 1,029 |
| Meagher | 319 | 32.68% | 629 | 64.45% | 28 | 2.87% | 976 |
| Mineral | 785 | 38.14% | 1,181 | 57.39% | 92 | 4.47% | 2,058 |
| Missoula | 41,688 | 67.62% | 18,631 | 30.22% | 1,332 | 2.16% | 61,651 |
| Musselshell | 573 | 23.56% | 1,743 | 71.67% | 116 | 4.77% | 2,432 |
| Park | 5,114 | 52.59% | 4,357 | 44.81% | 253 | 2.60% | 9,724 |
| Petroleum | 58 | 18.59% | 248 | 79.49% | 6 | 1.92% | 312 |
| Phillips | 577 | 27.71% | 1,426 | 68.49% | 79 | 3.79% | 2,082 |
| Pondera | 1,176 | 43.80% | 1,413 | 52.63% | 96 | 3.58% | 2,685 |
| Powder River | 203 | 20.86% | 748 | 76.88% | 22 | 2.26% | 973 |
| Powell | 1,026 | 37.17% | 1,641 | 59.46% | 93 | 3.37% | 2,760 |
| Prairie | 177 | 27.11% | 450 | 68.91% | 26 | 3.98% | 653 |
| Ravalli | 9,156 | 39.13% | 13,622 | 58.21% | 623 | 2.66% | 23,401 |
| Richland | 1,136 | 26.22% | 3,017 | 69.64% | 179 | 4.13% | 4,332 |
| Roosevelt | 2,013 | 58.40% | 1,346 | 39.05% | 88 | 2.55% | 3,447 |
| Rosebud | 1,511 | 44.88% | 1,765 | 52.42% | 91 | 2.70% | 3,367 |
| Sanders | 2,071 | 33.65% | 3,856 | 62.66% | 227 | 3.69% | 6,154 |
| Sheridan | 712 | 39.29% | 1,017 | 56.13% | 83 | 4.58% | 1,812 |
| Silver Bow | 11,672 | 71.55% | 4,246 | 26.03% | 394 | 2.42% | 16,312 |
| Stillwater | 1,501 | 30.86% | 3,206 | 65.91% | 157 | 3.23% | 4,864 |
| Sweet Grass | 652 | 31.08% | 1,372 | 65.40% | 74 | 3.53% | 2,098 |
| Teton | 1,290 | 40.86% | 1,784 | 56.51% | 83 | 2.63% | 3,157 |
| Toole | 626 | 32.90% | 1,208 | 63.48% | 69 | 3.63% | 1,903 |
| Treasure | 129 | 31.16% | 279 | 67.39% | 6 | 1.45% | 414 |
| Valley | 1,545 | 39.80% | 2,137 | 55.05% | 200 | 5.15% | 3,882 |
| Wheatland | 315 | 33.76% | 586 | 62.81% | 32 | 3.43% | 933 |
| Wibaux | 140 | 25.83% | 390 | 71.96% | 12 | 2.21% | 542 |
| Yellowstone | 32,225 | 46.53% | 34,682 | 50.08% | 2,351 | 3.39% | 69,258 |
Counties that flipped from Democratic to Republican
* Chouteau (largest municipality: Fort Benton)
* Rosebud (largest municipality: Colstrip)
* Yellowstone (largest municipality: Billings)