2020 United States Senate election in Iowa

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. Incumbent Republican Senator Joni Ernst won re-election to a second term, defeating Democratic nominee Theresa Greenfield.

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 bigger yet 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Withdrawn Paul Rieck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

Result

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Withdrawn Cal Woods, journalist and U.S. Navy veteran (endorsed Michael T. Franken) (remained on ballot)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 networkDateLink(s)ParticipantsTheresa GreenfieldMichael T. FrankenKimberly GrahamEddie MauroIowa PBSMay 18, 2020

Endorsements

Polling Poll source Date(s)administered Samplesize Marginof error MichaelFranken KimberlyGraham TheresaGreenfield EddieMauro UndecidedPublic Policy PollingPublic Policy Polling May 5–6, 2020 849 (V) –12%4%43%4%36%Emerson CollegeEmerson College October 13–16, 2019 317 (LV) ± 5.5% 6% 4% 11% 6% 74%

Results

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 HostDate & timeLink(s)ParticipantsJoni Ernst (R)Theresa Greenfield (D)Iowa Press DebatesSeptember 28, 2020

Predictions SourceRankingAs of The Cook Political Report October 29, 2020 Inside Elections October 28, 2020 Sabato's Crystal Ball November 2, 2020PoliticoNovember 2, 2020Daily Kos October 30, 2020RCPOctober 23, 2020DDHQNovember 3, 2020538November 2, 2020EconomistNovember 2, 2020

Additional general election endorsements

Polling Graphical summary

Aggregate polling +Theresa Greenfield vs. Joni ErnstSource of poll aggregationDates administeredDates updatedTheresa GreenfieldJoni ErnstOther/UndecidedMarginReal Clear PoliticsReal Clear PoliticsNovember 2, 2020November 3, 202045.8%47.2%7.0%Ernst +1.4270 to Win270 to WinNovember 2, 2020November 3, 202046.6% 47.0%6.4%Ernst +0.4

Poll source Date(s)administered Samplesize Marginof error JoniErnst (R) TheresaGreenfield (D) Other UndecidedPublic Policy Polling (D)Public Policy PollingNovember 1–2, 2020871 (V) –47%48% –5%Change Research (D)Change ResearchOctober 29 – November 1, 20201,084 (LV)± 3.2%47%48%3%1%Civiqs/Daily KosCiviqs/Daily KosOctober 29 – November 1, 2020853 (LV)± 3.7%47%50%1%1%Data for Progress (D)Data for Progress (D)October 27 – November 1, 2020951 (LV)± 3.2%45%49%6% –Emerson CollegeEmerson CollegeOctober 29–31, 2020604 (LV)± 3.9%48%51%2% –InsiderAdvantage (R)InsiderAdvantage (R) October 30, 2020400 (LV)± 4.9%51%45%2%3%Selzer & Co./Des Moines RegisterSelzer & Co./Des Moines RegisterOctober 26–29, 2020814 (LV)± 3.4%46%42%4%7%Quinnipiac UniversityQuinnipiac UniversityOctober 23–27, 20201,225 (LV)± 2.8%48%46%1%4%RABA ResearchRABA ResearchOctober 21–24, 2020693 (LV)± 4%45%51% – –Emerson CollegeEmerson CollegeOctober 19–21, 2020435 (LV)± 4.7%51%46%3% –RMG ResearchRMG Research October 15–21, 2020800 (LV)± 3.5%43%46%3%7%41%48%3%7%45%45%3%7%Siena College/NYT UpshotSiena College/NYT UpshotOctober 18–20, 2020753 (LV)± 3.9%45%44%6%6%Insider Advantage (R)Insider Advantage (R) October 18–19, 2020400 (LV)± 4.9%43%48%5%3%Monmouth UniversityMonmouth UniversityOctober 15–19, 2020501 (RV)± 4.4%47%47%3%2%501 (LV)47%49% – –501 (LV)45%51% – –Data for Progress (D)Data for Progress (D)October 8–11, 2020822 (LV)± 3.4%43%47%3%6%YouGov/CBSYouGov/CBSOctober 6–9, 20201,022 (LV)± 3.5%43%47%2%8%Opinion Insight (R)Opinion Insight (R)October 5–8, 2020800 (LV)± 3.46%47%45%4%4%Civiqs/Daily KosCiviqs/Daily KosOctober 3–6, 2020756 (LV)± 3.9%46%49%3%3%Quinnipiac UniversityQuinnipiac University October 1–5, 2020 1,205 (LV) ± 2.8% 45%50%1%4%Data for Progress (D)Data for Progress (D)September 23–28, 2020743 (LV)± 3.6%42%44%2%12%45%46% –9%Hart Research Associates (D)Hart Research Associates (D)September 24–27, 2020400 (LV)± 4.9%48%48% – –RABA ResearchRABA ResearchSeptember 23–26, 2020780 (LV)± 4%39%51% – –Monmouth UniversityMonmouth UniversitySeptember 18–22, 2020402 (RV)± 4.9%47%47%1%4%402 (LV)46%49%1%4%402 (LV)47%48%1%4%Siena College/NYT UpshotSiena College/NYT UpshotSeptember 16–22, 2020501 (LV)± 4.99%40%42%5%14%Selzer/Des Moines RegisterSelzer/Des Moines RegisterSeptember 14–17, 2020658 (LV)± 3.8%42%45%5%7%Fabrizio Ward (R)/Hart Research Associates (D)Fabrizio Ward/Hart Research AssociatesAugust 30 – September 5, 2020800 (LV)± 3.5%50%45%1%4%Opinion Insight (R)Opinion Insight (R)August 30 – September 2, 2020800 (LV)± 3.46%49%43%1%7%Public Policy Polling (D)Public Policy PollingAugust 13–14, 2020729 (V)± 4.1%45%48% –8%Monmouth UniversityMonmouth UniversityJuly 30 – August 3, 2020401 (RV)± 4.9%48%45%3%3%401 (LV)48%47%3%3%401 (LV)48%47%3%2%Data for Progress (D)Data for ProgressJuly 24 – August 2, 20201,101 (LV)± 3.2%43%45%11% –RMG ResearchRMG ResearchJuly 27–30, 2020500 (RV)± 4.5%36%40% –24%Spry Strategies (R)Spry Strategies (R)July 11–16, 2020701 (LV)± 3.7%43%45%6%7%GQR Research (D)GQR Research (D)June 23–28, 2020800 (LV)± 3.5%47%49% –4%Selzer/Des Moines RegisterSelzer/Des Moines RegisterJune 7–10, 2020674 (LV)± 3.8%43%46% –11%Civiqs/Daily KosCiviqs/Daily KosJune 6–8, 2020865 (RV)± 3.8%45%48% –6%Public Policy Polling (D)Public Policy Polling (D) June 3–4, 2020963 (V)± 3.4%43%45% –12%Public Policy Polling (D)Public Policy PollingApril 30 – May 1, 20201,222 (V)± 2.8%43%42% –14%Public Policy Polling (D)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)Lake Research Partners (D) April 24–29, 2019 500 (LV) ± 4.4% 56% 34% – –

with Eddie Mauro Poll source Date(s)administered Samplesize Marginof error JoniErnst (R) EddieMauro (D) UndecidedRABA Research/Eddie MauroRABA Research/Eddie MauroMay 7–9, 2020632 (LV) ± 3.9%42%42% –Lake Research Partners (D)April 24–29, 2019500 (LV)± 4.4% 58% 33% –49%44% –

with Joni Ernst and generic Democrat Poll source Date(s)administered Samplesize Marginof error JoniErnst (R) GenericDemocrat UndecidedPublic Policy PollingPublic Policy Polling April 29–30, 2019 780 (V) ± 3.5% 48% 44% –Public Policy Polling (D)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 Samplesize Marginof error JoniErnst (R) GenericOpponent Other UndecidedDes Moines Register/Selzer & Co.Des Moines Register/Selzer & Co.March 2–5, 2020667 (LV) ± 3.8%41%31%3%26%

with generic Republican and generic Democrat Poll source Date(s)administered Samplesize Marginof error GenericRepublican GenericDemocrat UndecidedLake Research Partners (D) April 24–29, 2019 500 (LV) ± 4.4% 45% 41% –

Results

By county