# 2020 United States Senate election in Iowa

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vte :
The 2020 United States Senate election in Iowa was held on November 3, 2020, to elect a member of the United States Senate to represent the State of Iowa, concurrently with the 2020 U.S. presidential election, as well as other elections to the United States Senate in other states and elections to the United States House of Representatives and various state and local elections. Primaries were held on June 2.
Most experts and pollsters considered this race and the concurrent presidential race as a tossup due to incumbent president Donald Trump's low approval ratings and Ernst's own popularity dropping in polls, partly due to a viral moment in a debate where she did not know the break-even price for soybeans. Despite this, Ernst was reelected by a larger-than-expected 6.6 points, while Trump simultaneously won the state with a similarly unexpected margin of victory. Ernst carried an overwhelming majority of the state's counties including many rural ones, while Greenfield carried only eight counties: Polk, Linn, Scott, Johnson, Black Hawk, Story, Cerro Gordo and Jefferson.

## Republican primary
### Candidates
#### Nominee

* Joni Ernst, incumbent U.S. senator

#### Withdrawn

* Paul Rieck

### Endorsements

Organizations
* Maggie's List

### Result

Republican primary results :
| Party | Party | Candidate | Votes | % |
| | Republican | Joni Ernst (incumbent) | 226,589 | 98.64% |
| | Republican | Write-In | 3,132 | 1.36% |
| Total votes | Total votes | Total votes | 229,721 | 100.00% |

## Democratic primary

On June 2, 2020, Theresa Greenfield won the Democratic primary with 47.71% of the vote, defeating three other major candidates, including Michael Franken, a retired U.S. Navy admiral and former aide to U.S. Senator Ted Kennedy.

### Candidates
#### Nominee

* Theresa Greenfield, businesswoman, candidate for Iowa's 3rd congressional district in 2018

#### Eliminated in primary

* Michael Franken, retired U.S. Navy admiral and former aide to U.S. Senator Ted Kennedy
* Kimberly Graham, child welfare attorney
* Eddie Mauro, businessman, teacher, candidate for Iowa's 3rd congressional district in 2018

#### Withdrawn

* Cal Woods, journalist and U.S. Navy veteran (endorsed Michael T. Franken) (remained on ballot)

#### Declined

* Cindy Axne, incumbent U.S. representative for Iowa's 3rd congressional district (running for reelection, endorsed Greenfield)
* Chet Culver, former governor of Iowa
* Deirdre DeJear, nominee for Secretary of State of Iowa in 2018
* Abby Finkenauer, incumbent U.S. representative for Iowa's 1st congressional district (running for reelection, endorsed Greenfield)
* Amber Gustafson, candidate for the Iowa Senate in 2018 (endorsed Greenfield)
* Rita Hart, former state senator and nominee for Lieutenant Governor of Iowa in 2018 (running in Iowa's 2nd congressional district)
* Rob Hogg, state senator
* Liz Mathis, state senator
* Rob Sand, Iowa State Auditor
* J.D. Scholten, nominee for Iowa's 4th congressional district in 2018 (running in Iowa's 4th congressional district)
* Tom Vilsack, former governor of Iowa and former U.S. Secretary of Agriculture
* Stacey Walker, Linn County supervisor (endorsed Graham)
* Steve Warnstadt, former state senator and intelligence officer in the Iowa Army National Guard

### Debates

| Host network | Date | Link(s) | Participants | Participants | Participants | Participants |
| Host network | Date | Link(s) | Theresa Greenfield | Michael T. Franken | Kimberly Graham | Eddie Mauro |
| Iowa PBS | May 18, 2020 | | Present | Present | Present | Present |

### Endorsements

Federal officials
* Chuck Hagel, former U.S. Secretary of Defense (2013–2015) and U.S. Senator from Nebraska (1997–2009) (Republican)
Individuals
* Paula Jean Swearengin, Democratic nominee in 2020 West Virginia U.S. Senate race
Organizations
* Association of Professional Flight Attendants
* Brand New Congress
* Sunrise Movement Cedar Rapids Chapter
* Sunrise Movement Dubuque Chapter
* Sunrise Movement University of Iowa Chapter
Federal officials
* Sherrod Brown, U.S. senator from Ohio
* Abby Finkenauer, U.S. representative (IA-01)
* Gabby Giffords, former U.S. representative (AZ-08) (2007–2012)
* Dave Loebsack, U.S. representative (IA-02)
* Barack Obama, former U.S. President
State officials
* Marti Anderson, state representative
* Tony Bisignano, state senator
* Joseph Bolkcom, state senator
* Robert Dvorsky, former state senator (1995–2019) and state representative (1987–1995)
* Ro Foege, former state representative (1996–2008)
* John Forbes, state representative
* Bruce Hunter, state representative
* Pam Jochum, state senator and former Iowa Senate president (2013–2017)
* Bob Kressig, state representative
* Monica Kurth, state representative
* Jim Lykam, state senator
* Mary Mascher, state representative
* Jo Oldson, state representative
* Sally Pederson, former lieutenant governor (1997–2007)
* Janet Petersen, state senator and Senate Minority Leader
* Amanda Ragan, state senator
* Joe Riding, former state representative (2013–2015)
* Sharon Steckman, state representative
* Kristin Sunde, state representative
* Zach Wahls, state senator
* Cindy Winckler, state representative
Individuals
* Jon Bauman, Social Security Works PAC president and former Sha Na Na member (1970–1983)
* Andy McGuire, former Iowa Democratic Party chair
* Christie Vilsack, former Iowa First Lady (1997–2007)
Unions
* American Federation of Government Employees
* American Federation of State, County and Municipal Employees Council 61
* International Association of Bridge, Structural, Ornamental and Reinforcing Iron Workers Local 89, 67, 111, 577, 21
* International Brotherhood of Electrical Workers Iowa State Conference
* International Brotherhood of Teamsters Local 238
* United Food and Commercial Workers Local 431
Organizations
* Brady Campaign
* DSCC
* EMILY's List
* End Citizens United
* Feminist Majority PAC
* Giffords
* League of Conservation Voters
* NARAL Pro-Choice America
* Population Connection

### Polling

| Poll source | Date(s) administered | Sample size | Margin of error | Michael Franken | Kimberly Graham | Theresa Greenfield | Eddie Mauro | Undecided |
| Public Policy Polling | May 5–6, 2020 | 849 (V) | – | 12% | 4% | 43% | 4% | 36% |
| Emerson College | October 13–16, 2019 | 317 (LV) | ± 5.5% | 6% | 4% | 11% | 6% | 74% |

### Results

Democratic primary results :
| Party | Party | Candidate | Votes | % |
| | Democratic | Theresa Greenfield | 132,001 | 47.71% |
| | Democratic | Michael T. Franken | 68,851 | 24.88% |
| | Democratic | Kimberly Graham | 41,554 | 15.02% |
| | Democratic | Eddie Mauro | 30,400 | 10.99% |
| | Democratic | Cal Woods (withdrawn) | 3,372 | 1.21% |
| | Democratic | Write-In | 514 | 0.19% |
| Total votes | Total votes | Total votes | 276,692 | 100.00% |

## Other candidates
### Libertarian Party
#### Nominee

* Rick Stewart, Libertarian nominee for the 2018 Iowa Secretary of Agriculture election and independent candidate for the 2014 United States Senate election in Iowa

### Independents
#### Declared

* Suzanne Herzog, economist and former ER nurse

## General election

Major media described the campaign as one of the most likely to decide control of the Senate after the 2020 election. Polls conducted after the primary showed a close contest between Greenfield and Ernst, with neither candidate leading by more than 4 points.
Through June 2020, Greenfield had raised $11.5 million, compared to $14.6 million for Ernst but by September, Greenfield had pulled ahead, raising $40.0 million compared to $21.6 million for Ernst. The race was expected to be the most expensive in the state's history, and the second most expensive Senate race in the United States, after the 2020 United States Senate election in North Carolina, where Cal Cunningham challenged Thom Tillis.

### Debate

| Host | Date & time | Link(s) | Participants | Participants |
| Host | Date & time | Link(s) | Joni Ernst (R) | Theresa Greenfield (D) |
| Iowa Press Debates | September 28, 2020 | | Present | Present |

### Predictions

| Source | Ranking | As of |
| The Cook Political Report | Tossup | October 29, 2020 |
| Inside Elections | Tossup | October 28, 2020 |
| Sabato's Crystal Ball | Lean R | November 2, 2020 |
| Politico | Tossup | November 2, 2020 |
| Daily Kos | Tossup | October 30, 2020 |
| RCP | Tossup | October 23, 2020 |
| DDHQ | Tossup | November 3, 2020 |
| 538 | Tossup | November 2, 2020 |
| Economist | Tossup | November 2, 2020 |

### Additional general election endorsements

Organizations
* Campaign for Working Families
* Huck PAC
Federal officials
* Joe Biden, 47th vice president of the United States, 2020 Democratic nominee for president
* Kirsten Gillibrand, U.S. senator from New York
* Elizabeth Warren, U.S. senator from Massachusetts
Unions
* National Education Association
* United Auto Workers
Newspapers
* Cedar Rapids Gazette
* Des Moines Register
* Dubuque Telegraph Herald
* Iowa City Press-Citizen
* Quad City Times
Organizations
* Center for Biological Diversity
* Climate Hawks Vote
* Council for a Livable World
* Democracy for America
* Everytown for Gun Safety
* J Street PAC
* National Committee to Preserve Social Security and Medicare
* Natural Resources Defense Council Action Fund

### Polling
#### Aggregate polling

Theresa Greenfield vs. Joni Ernst :
| Source of poll aggregation | Dates administered | Dates updated | Theresa Greenfield | Joni Ernst | Other/Undecided | Margin |
| Real Clear Politics | November 2, 2020 | November 3, 2020 | 45.8% | 47.2% | 7.0% | Ernst +1.4 |
| 270 to Win | November 2, 2020 | November 3, 2020 | 46.6% | 47.0% | 6.4% | Ernst +0.4 |
| Poll source | Date(s) administered | Sample size | Margin of error | Joni Ernst (R) | Theresa Greenfield (D) | Other/ Undecided |
| Public Policy Polling | November 1–2, 2020 | 871 (V) | – | 47% | 48% | 5% |
| Change Research | October 29 – November 1, 2020 | 1,084 (LV) | ± 3.2% | 47% | 48% | 4% |
| Civiqs/Daily Kos | October 29 – November 1, 2020 | 853 (LV) | ± 3.7% | 47% | 50% | 2% |
| Data for Progress | October 27 – November 1, 2020 | 951 (LV) | ± 3.2% | 45% | 49% | 6% |
| Emerson College | October 29–31, 2020 | 604 (LV) | ± 3.9% | 48% | 51% | 2% |
| InsiderAdvantage (R) | October 30, 2020 | 400 (LV) | ± 4.9% | 51% | 45% | 4% |
| Selzer & Co./Des Moines Register | October 26–29, 2020 | 814 (LV) | ± 3.4% | 46% | 42% | 11% |
| Quinnipiac University | October 23–27, 2020 | 1,225 (LV) | ± 2.8% | 48% | 46% | 1% |
| RABA Research | October 21–24, 2020 | 693 (LV) | ± 4% | 45% | 51% | – |
| Emerson College | October 19–21, 2020 | 435 (LV) | ± 4.7% | 51% | 46% | 3% |
| RMG Research | October 15–21, 2020 | 800 (LV) | ± 3.5% | 43% | 46% | 10% |
| RMG Research | October 15–21, 2020 | 800 (LV) | ± 3.5% | 41% | 48% | 10% |
| RMG Research | October 15–21, 2020 | 800 (LV) | ± 3.5% | 45% | 45% | 10% |
| Siena College/NYT Upshot | October 18–20, 2020 | 753 (LV) | ± 3.9% | 45% | 44% | 12% |
| Insider Advantage (R) | October 18–19, 2020 | 400 (LV) | ± 4.9% | 43% | 48% | 8% |
| Monmouth University | October 15–19, 2020 | 501 (RV) | ± 4.4% | 47% | 47% | 5% |
| Monmouth University | October 15–19, 2020 | 501 (LV) | ± 4.4% | 47% | 49% | – |
| Monmouth University | October 15–19, 2020 | 501 (LV) | ± 4.4% | 45% | 51% | – |
| Data for Progress (D) | October 8–11, 2020 | 822 (LV) | ± 3.4% | 43% | 47% | 10% |
| YouGov/CBS | October 6–9, 2020 | 1,022 (LV) | ± 3.5% | 43% | 47% | 10% |
| Opinion Insight (R) | October 5–8, 2020 | 800 (LV) | ± 3.46% | 47% | 45% | 8% |
| Civiqs/Daily Kos | October 3–6, 2020 | 756 (LV) | ± 3.9% | 46% | 49% | 6% |
| Quinnipiac University | October 1–5, 2020 | 1,205 (LV) | ± 2.8% | 45% | 50% | 5% |
| Data for Progress (D) | September 23–28, 2020 | 743 (LV) | ± 3.6% | 42% | 44% | 14% |
| Data for Progress (D) | September 23–28, 2020 | 743 (LV) | ± 3.6% | 45% | 46% | 9% |
| Hart Research Associates (D) | September 24–27, 2020 | 400 (LV) | ± 4.9% | 48% | 48% | – |
| RABA Research | September 23–26, 2020 | 780 (LV) | ± 4% | 39% | 51% | – |
| Monmouth University | September 18–22, 2020 | 402 (RV) | ± 4.9% | 47% | 47% | 5% |
| Monmouth University | September 18–22, 2020 | 402 (LV) | ± 4.9% | 46% | 49% | 5% |
| Monmouth University | September 18–22, 2020 | 402 (LV) | ± 4.9% | 47% | 48% | 5% |
| Siena College/NYT Upshot | September 16–22, 2020 | 501 (LV) | ± 4.99% | 40% | 42% | 19% |
| Selzer/Des Moines Register | September 14–17, 2020 | 658 (LV) | ± 3.8% | 42% | 45% | 12% |
| Fabrizio Ward/Hart Research Associates | August 30 – September 5, 2020 | 800 (LV) | ± 3.5% | 50% | 45% | 5% |
| Opinion Insight (R) | August 30 – September 2, 2020 | 800 (LV) | ± 3.46% | 49% | 43% | 7% |
| Public Policy Polling | August 13–14, 2020 | 729 (V) | ± 4.1% | 45% | 48% | 8% |
| Monmouth University | July 30 – August 3, 2020 | 401 (RV) | ± 4.9% | 48% | 45% | 6% |
| Monmouth University | July 30 – August 3, 2020 | 401 (LV) | ± 4.9% | 48% | 47% | 6% |
| Monmouth University | July 30 – August 3, 2020 | 401 (LV) | ± 4.9% | 48% | 47% | 5% |
| Data for Progress | July 24 – August 2, 2020 | 1,101 (LV) | ± 3.2% | 43% | 45% | 11% |
| RMG Research | July 27–30, 2020 | 500 (RV) | ± 4.5% | 36% | 40% | 24% |
| Spry Strategies (R) | July 11–16, 2020 | 701 (LV) | ± 3.7% | 43% | 45% | 12% |
| GQR Research (D) | June 23–28, 2020 | 800 (LV) | ± 3.5% | 47% | 49% | 4% |
| Selzer/Des Moines Register | June 7–10, 2020 | 674 (LV) | ± 3.8% | 43% | 46% | 11% |
| Civiqs/Daily Kos | June 6–8, 2020 | 865 (RV) | ± 3.8% | 45% | 48% | 6% |
| Public Policy Polling (D) | June 3–4, 2020 | 963 (V) | ± 3.4% | 43% | 45% | 12% |
| Public Policy Polling | April 30 – May 1, 2020 | 1,222 (V) | ± 2.8% | 43% | 42% | 14% |
| Public Policy Polling (D) | December 13–15, 2019 | 944 (V) | ± 3.4% | 47% | 41% | 12% |
| Emerson College | October 13–16, 2019 | 888 (RV) | ± 3.2% | 47% | 40% | 14% |
| Lake Research Partners (D) | April 24–29, 2019 | 500 (LV) | ± 4.4% | 56% | 34% | – |
with Eddie Mauro
| Poll source | Date(s) administered | Sample size | Margin of error | Joni Ernst (R) | Eddie Mauro (D) | Undecided |
| RABA Research/Eddie Mauro | May 7–9, 2020 | 632 (LV) | ± 3.9% | 42% | 42% | – |
| Lake Research Partners (D) | April 24–29, 2019 | 500 (LV) | ± 4.4% | 58% | 33% | – |
| Lake Research Partners (D) | April 24–29, 2019 | 500 (LV) | ± 4.4% | 49% | 44% | – |
with Joni Ernst and generic Democrat
| Poll source | Date(s) administered | Sample size | Margin of error | Joni Ernst (R) | Generic Democrat | Undecided |
| Public Policy Polling | April 29–30, 2019 | 780 (V) | ± 3.5% | 48% | 44% | – |
| Public Policy Polling (D) | June 30 – July 1, 2017 | 784 (V) | ± 3.6% | 48% | 41% | 12% |
with Joni Ernst and Generic Opponent
| Poll source | Date(s) administered | Sample size | Margin of error | Joni Ernst (R) | Generic Opponent | Other | Undecided |
| Des Moines Register/Selzer & Co. | March 2–5, 2020 | 667 (LV) | ± 3.8% | 41% | 31% | 3% | 26% |
with generic Republican and generic Democrat
| Poll source | Date(s) administered | Sample size | Margin of error | Generic Republican | Generic Democrat | Undecided |
| Lake Research Partners (D) | April 24–29, 2019 | 500 (LV) | ± 4.4% | 45% | 41% | – |

### Results

2020 United States Senate election in Iowa :
| Party | Party | Candidate | Votes | % | ±% |
| | Republican | Joni Ernst (incumbent) | 864,997 | 51.74% | −0.36% |
| | Democratic | Theresa Greenfield | 754,859 | 45.15% | +1.39% |
| | Libertarian | Rick Stewart | 36,961 | 2.21% | +1.48% |
| | Independent | Suzanne Herzog | 13,800 | 0.83% | N/A |
| | Write-in | Write-in | 1,211 | 0.07% | -0.03% |
| Total votes | Total votes | Total votes | 1,671,828 | 100.0% | |
| | Republican hold | Republican hold | Republican hold | Republican hold | Republican hold |

#### By county

By county :
| County | Joni Ernst Republican | Joni Ernst Republican | Theresa Greenfield Democratic | Theresa Greenfield Democratic | Rick Stewart Libertarian | Rick Stewart Libertarian | Suzanne Herzog Independent | Suzanne Herzog Independent | Write-in | Write-in | Margin | Margin | Total votes |
| County | # | % | # | % | # | % | # | % | # | % | # | % | Total votes |
| Adair | 2,809 | 67.78 | 1,207 | 29.13 | 89 | 2.15 | 36 | 0.87 | 3 | 0.07 | 1,602 | 38.66 | 4,144 |
| Adams | 1,497 | 69.34 | 594 | 27.51 | 46 | 2.13 | 19 | 0.88 | 3 | 0.14 | 903 | 41.82 | 2,159 |
| Allamakee | 4,478 | 61.04 | 2,602 | 35.47 | 175 | 2.39 | 80 | 1.09 | 1 | 0.01 | 1,876 | 25.57 | 7,336 |
| Appanoose | 4,189 | 65.60 | 1,956 | 30.63 | 168 | 2.63 | 71 | 1.11 | 2 | 0.03 | 2,233 | 34.97 | 6,386 |
| Audubon | 2,188 | 64.89 | 1,092 | 32.38 | 70 | 2.08 | 21 | 0.62 | 1 | 0.03 | 1,096 | 32.50 | 3,372 |
| Benton | 8,830 | 60.93 | 5,202 | 35.90 | 331 | 2.28 | 120 | 0.83 | 9 | 0.06 | 3,628 | 25.03 | 14,492 |
| Black Hawk | 29,222 | 44.27 | 34,963 | 52.96 | 1,301 | 1.97 | 490 | 0.74 | 37 | 0.06 | -5,741 | -8.70 | 66,013 |
| Boone | 8,315 | 54.74 | 6,316 | 41.58 | 385 | 2.53 | 167 | 1.10 | 7 | 0.05 | 1,999 | 13.16 | 15,190 |
| Bremer | 8,196 | 56.72 | 5,911 | 40.91 | 254 | 1.76 | 84 | 0.58 | 5 | 0.03 | 2,285 | 15.81 | 14,450 |
| Buchanan | 6,063 | 56.64 | 4,292 | 40.10 | 248 | 2.32 | 96 | 0.90 | 5 | 0.05 | 1,771 | 16.55 | 10,704 |
| Buena Vista | 4,724 | 59.09 | 3,022 | 37.80 | 166 | 2.08 | 75 | 0.94 | 7 | 0.09 | 1,702 | 21.29 | 7,994 |
| Butler | 5,291 | 66.06 | 2,474 | 30.89 | 173 | 2.16 | 69 | 0.86 | 2 | 0.02 | 2,817 | 35.17 | 8,009 |
| Calhoun | 3,513 | 67.40 | 1,531 | 29.37 | 129 | 2.48 | 32 | 0.61 | 7 | 0.13 | 1,982 | 38.03 | 5,212 |
| Carroll | 7,245 | 64.91 | 3,580 | 32.07 | 230 | 2.06 | 96 | 0.86 | 11 | 0.10 | 3,665 | 32.83 | 11,162 |
| Cass | 4,725 | 65.95 | 2,259 | 31.53 | 120 | 1.67 | 54 | 0.75 | 7 | 0.10 | 2,466 | 34.42 | 7,165 |
| Cedar | 5,935 | 56.30 | 4,300 | 40.79 | 226 | 2.14 | 74 | 0.70 | 6 | 0.06 | 1,635 | 15.51 | 10,541 |
| Cerro Gordo | 11,339 | 48.19 | 11,534 | 49.02 | 430 | 1.83 | 211 | 0.90 | 16 | 0.07 | -195 | -0.83 | 23,530 |
| Cherokee | 4,214 | 65.59 | 2,002 | 31.16 | 138 | 2.15 | 67 | 1.04 | 4 | 0.06 | 2,212 | 34.43 | 6,425 |
| Chickasaw | 4,024 | 61.16 | 2,324 | 35.32 | 159 | 2.42 | 71 | 1.08 | 2 | 0.03 | 1,700 | 25.84 | 6,580 |
| Clarke | 2,906 | 63.05 | 1,520 | 32.98 | 119 | 2.58 | 60 | 1.30 | 4 | 0.09 | 1,386 | 30.07 | 4,609 |
| Clay | 5,716 | 64.46 | 2,861 | 32.26 | 193 | 2.18 | 89 | 1.00 | 9 | 0.10 | 2,855 | 32.19 | 8,868 |
| Clayton | 5,845 | 61.37 | 3,434 | 36.06 | 157 | 1.65 | 82 | 0.86 | 6 | 0.06 | 2,411 | 25.31 | 9,524 |
| Clinton | 12,559 | 51.57 | 10,942 | 44.93 | 635 | 2.61 | 200 | 0.82 | 15 | 0.06 | 1,617 | 6.64 | 24,351 |
| Crawford | 4,424 | 63.12 | 2,336 | 33.33 | 160 | 2.28 | 80 | 1.14 | 9 | 0.13 | 2,088 | 29.79 | 7,009 |
| Dallas | 28,727 | 51.69 | 25,427 | 45.75 | 1,006 | 1.81 | 381 | 0.69 | 33 | 0.06 | 3,300 | 5.94 | 55,574 |
| Davis | 2,728 | 67.51 | 1,167 | 28.88 | 112 | 2.77 | 32 | 0.79 | 2 | 0.05 | 1,561 | 38.63 | 4,041 |
| Decatur | 2,439 | 65.21 | 1,165 | 31.15 | 90 | 2.41 | 43 | 1.15 | 3 | 0.08 | 1,274 | 34.06 | 3,740 |
| Delaware | 6,454 | 64.96 | 3,235 | 32.56 | 172 | 1.73 | 71 | 0.71 | 4 | 0.04 | 3,219 | 32.40 | 9,936 |
| Des Moines | 9,468 | 48.27 | 9,296 | 47.39 | 591 | 3.01 | 232 | 1.18 | 29 | 0.15 | 172 | 0.88 | 19,616 |
| Dickinson | 7,149 | 63.92 | 3,791 | 33.90 | 174 | 1.56 | 66 | 0.59 | 4 | 0.04 | 3,358 | 30.03 | 11,184 |
| Dubuque | 26,034 | 49.05 | 25,433 | 47.91 | 1,148 | 2.16 | 428 | 0.81 | 37 | 0.07 | 601 | 1.13 | 53,080 |
| Emmet | 2,965 | 61.81 | 1,637 | 34.13 | 147 | 3.06 | 47 | 0.98 | 1 | 0.02 | 1,328 | 27.68 | 4,797 |
| Fayette | 5,865 | 58.06 | 3,912 | 38.73 | 229 | 2.27 | 89 | 0.88 | 7 | 0.07 | 1,953 | 19.33 | 10,102 |
| Floyd | 4,181 | 52.45 | 3,498 | 43.88 | 187 | 2.35 | 98 | 1.23 | 8 | 0.10 | 683 | 8.57 | 7,972 |
| Franklin | 3,270 | 64.55 | 1,639 | 32.35 | 100 | 1.97 | 50 | 0.99 | 7 | 0.14 | 1,631 | 32.20 | 5,066 |
| Fremont | 2,563 | 67.31 | 1,099 | 28.86 | 89 | 2.34 | 56 | 1.47 | 1 | 0.03 | 1,464 | 38.45 | 3,808 |
| Greene | 3,063 | 61.36 | 1,784 | 35.74 | 104 | 2.08 | 39 | 0.78 | 2 | 0.04 | 1,279 | 25.62 | 4,992 |
| Grundy | 4,900 | 67.90 | 2,120 | 29.38 | 154 | 2.13 | 38 | 0.53 | 5 | 0.07 | 2,780 | 38.52 | 7,217 |
| Guthrie | 4,103 | 64.86 | 2,000 | 31.62 | 162 | 2.56 | 56 | 0.89 | 5 | 0.08 | 2,103 | 33.24 | 6,326 |
| Hamilton | 4,679 | 59.42 | 2,913 | 36.99 | 190 | 2.41 | 84 | 1.07 | 9 | 0.11 | 1,766 | 22.43 | 7,875 |
| Hancock | 4,004 | 65.86 | 1,881 | 30.94 | 130 | 2.14 | 60 | 0.99 | 5 | 0.08 | 2,123 | 34.92 | 6,080 |
| Hardin | 5,639 | 63.80 | 2,920 | 33.04 | 195 | 2.21 | 84 | 0.95 | 1 | 0.01 | 2,719 | 30.76 | 8,839 |
| Harrison | 5,059 | 63.10 | 2,574 | 32.10 | 253 | 3.16 | 118 | 1.47 | 14 | 0.17 | 2,485 | 30.99 | 8,018 |
| Henry | 5,875 | 60.12 | 3,457 | 35.38 | 310 | 3.17 | 116 | 1.19 | 14 | 0.14 | 2,418 | 24.74 | 9,772 |
| Howard | 2,716 | 55.36 | 2,014 | 41.05 | 118 | 2.41 | 58 | 1.18 | 0 | 0.00 | 702 | 14.31 | 4,906 |
| Humboldt | 3,671 | 69.74 | 1,443 | 27.41 | 108 | 2.05 | 40 | 0.76 | 2 | 0.04 | 2,228 | 42.33 | 5,264 |
| Ida | 2,757 | 72.23 | 964 | 25.26 | 66 | 1.73 | 28 | 0.73 | 2 | 0.05 | 1,793 | 46.97 | 3,817 |
| Iowa | 5,794 | 60.13 | 3,541 | 36.75 | 205 | 2.13 | 84 | 0.87 | 11 | 0.11 | 2,253 | 23.38 | 9,635 |
| Jackson | 6,175 | 56.58 | 4,249 | 38.94 | 366 | 3.35 | 118 | 1.08 | 5 | 0.05 | 1,926 | 17.65 | 10,913 |
| Jasper | 11,405 | 56.95 | 7,905 | 39.47 | 531 | 2.65 | 167 | 0.83 | 18 | 0.09 | 3,500 | 17.48 | 20,026 |
| Jefferson | 4,008 | 45.50 | 4,547 | 51.62 | 163 | 1.85 | 80 | 0.91 | 10 | 0.11 | -539 | -6.12 | 8,808 |
| Johnson | 23,773 | 28.77 | 57,063 | 69.06 | 1,382 | 1.67 | 373 | 0.45 | 42 | 0.05 | -33,290 | -40.29 | 82,633 |
| Jones | 6,320 | 57.97 | 4,237 | 38.86 | 273 | 2.50 | 68 | 0.62 | 4 | 0.04 | 2,083 | 19.11 | 10,902 |
| Keokuk | 3,565 | 68.39 | 1,489 | 28.56 | 101 | 1.94 | 53 | 1.02 | 5 | 0.10 | 2,076 | 39.82 | 5,213 |
| Kossuth | 5,957 | 66.14 | 2,799 | 31.08 | 193 | 2.14 | 57 | 0.63 | 0 | 0.00 | 3,158 | 35.07 | 9,006 |
| Lee | 8,489 | 51.29 | 7,445 | 44.98 | 485 | 2.93 | 122 | 0.74 | 11 | 0.07 | 1,044 | 6.31 | 16,552 |
| Linn | 53,248 | 42.10 | 69,125 | 54.66 | 3,188 | 2.52 | 815 | 0.64 | 90 | 0.07 | -15,877 | -12.55 | 126,466 |
| Louisa | 3,259 | 61.97 | 1,804 | 34.30 | 141 | 2.68 | 51 | 0.97 | 4 | 0.08 | 1,455 | 27.67 | 5,259 |
| Lucas | 3,105 | 68.32 | 1,302 | 28.65 | 99 | 2.18 | 36 | 0.79 | 3 | 0.07 | 1,803 | 39.67 | 4,545 |
| Lyon | 5,522 | 81.80 | 1,073 | 15.89 | 104 | 1.54 | 50 | 0.74 | 2 | 0.03 | 4,449 | 65.90 | 6,751 |
| Madison | 6,245 | 64.25 | 3,168 | 32.59 | 218 | 2.24 | 86 | 0.88 | 3 | 0.03 | 3,077 | 31.66 | 9,720 |
| Mahaska | 7,860 | 70.00 | 2,969 | 26.44 | 273 | 2.43 | 118 | 1.05 | 8 | 0.07 | 4,891 | 43.56 | 11,228 |
| Marion | 12,211 | 64.06 | 6,269 | 32.89 | 423 | 2.22 | 144 | 0.76 | 15 | 0.08 | 5,942 | 31.17 | 19,062 |
| Marshall | 9,057 | 50.68 | 8,187 | 45.81 | 442 | 2.47 | 165 | 0.92 | 21 | 0.12 | 870 | 4.87 | 17,872 |
| Mills | 5,347 | 65.54 | 2,544 | 31.18 | 177 | 2.17 | 82 | 1.01 | 8 | 0.10 | 2,803 | 34.36 | 8,158 |
| Mitchell | 3,347 | 57.69 | 2,282 | 39.33 | 124 | 2.14 | 49 | 0.84 | 0 | 0.00 | 1,065 | 18.36 | 5,802 |
| Monona | 3,054 | 65.47 | 1,455 | 31.19 | 108 | 2.32 | 39 | 0.84 | 9 | 0.19 | 1,599 | 34.28 | 4,665 |
| Monroe | 2,742 | 68.40 | 1,148 | 28.64 | 84 | 2.10 | 34 | 0.85 | 1 | 0.02 | 1,594 | 39.76 | 4,009 |
| Montgomery | 3,633 | 68.53 | 1,520 | 28.67 | 98 | 1.85 | 46 | 0.87 | 4 | 0.08 | 2,113 | 39.86 | 5,301 |
| Muscatine | 10,278 | 50.28 | 9,381 | 45.89 | 570 | 2.79 | 199 | 0.97 | 13 | 0.06 | 897 | 4.39 | 20,441 |
| O'Brien | 5,675 | 76.05 | 1,640 | 21.98 | 105 | 1.41 | 38 | 0.51 | 4 | 0.05 | 4,035 | 54.07 | 7,462 |
| Osceola | 2,525 | 77.38 | 657 | 20.13 | 49 | 1.50 | 31 | 0.95 | 1 | 0.03 | 1,868 | 57.25 | 3,263 |
| Page | 5,152 | 69.27 | 2,067 | 27.79 | 138 | 1.86 | 78 | 1.05 | 3 | 0.04 | 3,085 | 41.48 | 7,438 |
| Palo Alto | 3,113 | 63.12 | 1,677 | 34.00 | 106 | 2.15 | 36 | 0.73 | 0 | 0.00 | 1,436 | 29.12 | 4,932 |
| Plymouth | 10,145 | 72.26 | 3,587 | 25.55 | 219 | 1.56 | 77 | 0.55 | 11 | 0.08 | 6,558 | 46.71 | 14,039 |
| Pocahontas | 2,641 | 69.87 | 1,003 | 26.53 | 91 | 2.41 | 39 | 1.03 | 6 | 0.16 | 1,638 | 43.33 | 3,780 |
| Polk | 106,443 | 41.54 | 142,328 | 55.54 | 5,313 | 2.07 | 1,985 | 0.77 | 188 | 0.07 | -35,885 | -14.00 | 256,257 |
| Pottawattamie | 24,720 | 54.85 | 18,520 | 41.10 | 1,269 | 2.82 | 524 | 1.16 | 32 | 0.07 | 6,200 | 13.76 | 45,065 |
| Poweshiek | 5,361 | 53.38 | 4,381 | 43.62 | 202 | 2.01 | 91 | 0.91 | 8 | 0.08 | 980 | 9.76 | 10,043 |
| Ringgold | 1,870 | 69.36 | 732 | 27.15 | 75 | 2.78 | 16 | 0.59 | 3 | 0.11 | 1,138 | 42.21 | 2,696 |
| Sac | 3,849 | 70.17 | 1,440 | 26.25 | 129 | 2.35 | 60 | 1.09 | 7 | 0.13 | 2,409 | 43.92 | 5,485 |
| Scott | 42,941 | 46.88 | 45,751 | 49.94 | 2,139 | 2.33 | 709 | 0.77 | 66 | 0.07 | -2,810 | -3.07 | 91,606 |
| Shelby | 4,489 | 67.06 | 1,989 | 29.71 | 156 | 2.33 | 57 | 0.85 | 3 | 0.04 | 2,500 | 37.35 | 6,694 |
| Sioux | 15,785 | 83.54 | 2,828 | 14.97 | 192 | 1.02 | 81 | 0.43 | 9 | 0.05 | 12,957 | 68.57 | 18,895 |
| Story | 20,750 | 41.08 | 28,216 | 55.86 | 1,133 | 2.24 | 370 | 0.73 | 44 | 0.09 | -7,466 | -14.78 | 50,513 |
| Tama | 5,090 | 56.74 | 3,588 | 40.00 | 205 | 2.29 | 79 | 0.88 | 8 | 0.09 | 1,502 | 16.74 | 8,970 |
| Taylor | 2,337 | 72.80 | 762 | 23.74 | 83 | 2.59 | 28 | 0.87 | 0 | 0.00 | 1,575 | 49.07 | 3,210 |
| Union | 3,820 | 62.38 | 2,051 | 33.49 | 172 | 2.81 | 76 | 1.24 | 5 | 0.08 | 1,769 | 28.89 | 6,124 |
| Van Buren | 2,583 | 68.84 | 1,065 | 28.38 | 75 | 2.00 | 28 | 0.75 | 1 | 0.03 | 1,518 | 40.46 | 3,752 |
| Wapello | 8,464 | 55.15 | 6,344 | 41.33 | 394 | 2.57 | 132 | 0.86 | 14 | 0.09 | 2,120 | 13.81 | 15,348 |
| Warren | 17,276 | 56.27 | 12,478 | 40.64 | 692 | 2.25 | 234 | 0.76 | 23 | 0.07 | 4,798 | 15.63 | 30,703 |
| Washington | 6,773 | 58.12 | 4,519 | 38.78 | 262 | 2.25 | 95 | 0.82 | 5 | 0.04 | 2,254 | 19.34 | 11,654 |
| Wayne | 2,186 | 71.55 | 784 | 25.66 | 53 | 1.73 | 28 | 0.92 | 4 | 0.13 | 1,402 | 45.89 | 3,055 |
| Webster | 10,195 | 57.81 | 6,845 | 38.81 | 403 | 2.29 | 173 | 0.98 | 19 | 0.11 | 3,350 | 19.00 | 17,635 |
| Winnebago | 3,336 | 56.29 | 2,361 | 39.84 | 153 | 2.58 | 72 | 1.21 | 4 | 0.07 | 975 | 16.45 | 5,926 |
| Winneshiek | 6,039 | 50.49 | 5,581 | 46.66 | 218 | 1.82 | 118 | 0.99 | 4 | 0.03 | 458 | 3.83 | 11,960 |
| Woodbury | 24,175 | 54.27 | 18,674 | 41.92 | 994 | 2.23 | 629 | 1.41 | 72 | 0.16 | 5,501 | 12.35 | 44,544 |
| Worth | 2,425 | 55.40 | 1,803 | 41.19 | 98 | 2.24 | 46 | 1.05 | 5 | 0.11 | 622 | 14.21 | 4,377 |
| Wright | 3,889 | 62.85 | 2,063 | 33.34 | 158 | 2.55 | 76 | 1.23 | 2 | 0.03 | 1,826 | 29.51 | 6,188 |
| Totals | 864,997 | 51.74 | 754,859 | 45.15 | 36,961 | 2.21 | 13,800 | 0.83 | 1,211 | 0.07 | 110,138 | 6.59 | 1,671,828 |

#### By congressional district

By congressional district :
| District | Joni Ernst Republican | Joni Ernst Republican | Theresa Greenfield Democratic | Theresa Greenfield Democratic | Rick Stewart Libertarian | Rick Stewart Libertarian | Suzanne Herzog Independent | Suzanne Herzog Independent | Write-in | Write-in | Margin | Margin | Total votes | Representative (2020) |
| District | # | % | # | % | # | % | # | % | # | % | # | % | Total votes | Representative (2020) |
| 1st district | 206,559 | 49.48 | 197,792 | 47.72 | 9,454 | 2.26 | 3,231 | 0.77 | 267 | 0.06 | 8,767 | 2.10 | 417,483 | Ashley Hinson |
| 2nd district | 199,741 | 49.17 | 193,588 | 47.65 | 9,426 | 2.32 | 3,197 | 0.79 | 295 | 0.07 | 6,153 | 1.51 | 406,247 | Mariannette Miller-Meeks |
| 3rd district | 221,267 | 48.75 | 218,756 | 48.20 | 9,747 | 2.15 | 3,757 | 0.83 | 321 | 0.07 | 2,511 | 0.55 | 453,848 | Cindy Axne |
| 4th district | 237,430 | 60.22 | 144,543 | 36.66 | 8,334 | 2.11 | 3,615 | 0.92 | 328 | 0.08 | 92,887 | 23.56 | 394,250 | Randy Feenstra |
| Totals | 864,997 | 51.74 | 754,859 | 45.15 | 36,961 | 2.21 | 13,800 | 0.83 | 1,211 | 0.07 | 110,138 | 6.59 | 1,671,828 |