The 2020 United States Senate election in Maine was held on November 3, 2020, to elect a member of the United States Senate to represent the state of Maine. Republican incumbent Susan Collins won re-election to a fifth term, defeating Democratic speaker Sara Gideon.

The race became the most expensive in Maine's history, with Collins spending $23 million and Gideon $48 million. It also had national implications, as defeating Collins was a key part of the Democrats' strategy to achieve a Senate majority. While Gideon led Collins in nearly every public poll, Collins unexpectedly defeated Gideon by 8.6 points on election day. Collins outperformed Republican President Donald Trump, who lost the state to Democratic nominee Joe Biden by more than nine percent. Maine was the only state to elect a senator of a different party than the winner of its presidential contest in the November 3 election.

Maine used a ranked choice voting system in the 2020 U.S. Senate election, as established by a 2016 referendum. Because Collins won a majority of the first-place votes cast, no additional vote tabulation rounds were needed. This was the first Senate election in Maine since 1996 where Democrats won a county.

Background Republican U.S. Senator Susan Collins ran for a fifth term. Collins had won each election to this seat by a greater victory margin than the one before it. Observers did not expect this election to continue that trend.Multiple sources:

Collins was criticized for her decision to vote to confirm Brett Kavanaugh to the United States Supreme Court despite his anti-abortion stances (Collins is pro-choice) and allegations of sexual misconduct and abuse against him, though she gave a highly publicized speech on the Senate floor explaining her reasoning. She also faced criticism for her stance on the impeachment of President Donald Trump. Collins voted in favor of allowing witness testimony in the Senate trial, and was the first Republican to do so, and she voted to acquit Trump on both charges of abuse of power and obstruction of Congress.Multiple sources: She said she voted to acquit because "impeachment of a president should be reserved for conduct that poses such a serious threat to our governmental institutions as to warrant the extreme step of immediate removal from office." She initially claimed that Trump "learned a pretty big lesson" from the impeachment, but later said that she thought he had not learned from it after all. She was also criticized for running for third, fourth, and fifth Senate terms despite vowing to serve no more than two terms during her 1996 campaign, though she has explained this as a product of having learned the value of seniority in the Senate. The emphasis on seniority became a key theme of her campaign. Collins was widely considered one of the two least conservative Republican U.S. senators (the other being Lisa Murkowski).

During Trump's presidency, Collins's stance on Trump waffled, as he did not share her moderate politics but had a strong base in Maine's sprawling, rural 2nd congressional district. Collins voted against the Affordable Care Act repeal, but for the GOP's 2017 tax bill and to acquit Trump in his first impeachment. She voted to confirm Trump's nominees Brett Kavanaugh and Neil Gorsuch to the Supreme Court but against the confirmation of Amy Coney Barrett just days before the 2020 election, citing disagreement with process.

The Democratic nominee, Speaker of the Maine House of Representatives Sara Gideon, supported criminal justice reforms, expansion of the Affordable Care Act, rejoining the Paris Climate Accord, and imposing universal background checks on gun sales to combat gun violence. In 2019, Gideon faced an election ethics complaint for accepting reimbursements for her political donations from her own PAC. Gideon apologized for the violation, reimbursed the federal government a total of $3,250, and closed the PAC. Gideon was also criticized for keeping the Maine House of Representatives adjourned for most of the year (neighboring New Hampshire had reconvened its sizably larger legislature by late spring) and for allegedly turning a blind eye to a legislative colleague accused of molesting underage girls until she was forced to acknowledge the scandal.

Lisa Savage, an antiwar activist and schoolteacher from Solon, initially sought the Maine Green Independent Party nomination, but in late February, she announced her intention to instead qualify for the ballot as an independent due to Maine's ballot access measures.

Max Linn, a financial planner and conservative activist from Bar Harbor, was a Trump supporter and former candidate of the Republican and Reform parties. In July 2020, he qualified for the ballot as an independent. Former Republican state senator Mary Small challenged the signatures on his petition, but the secretary of state found that he had enough and he was placed on the ballot. Later that month, he announced his intention to drop out of the race to support Collins. But days later, he decided not to drop out unless Collins agreed to a list of policies, which she did not.

Party primaries were initially scheduled to take place on June 9, but due to the COVID-19 pandemic and its impact on the state, Governor Janet Mills rescheduled them for July 14. Mills's executive order also expanded voters' ability to request absentee ballots, which could then be done up to and on election day. The primaries were conducted with ranked choice voting. Parties qualified to participate in the 2020 primary election were the Democratic Party, the Republican Party, and the Maine Green Independent Party.

Republican primary Candidates Nominee Susan Collins, incumbent U.S. senator

Eliminated in primary Amy Colter, law office manager (write-in candidate)

Withdrawn Derek Levasseur, police officer

Declined Paul LePage, former governor of Maine (endorsed Collins) Max Linn, financial planner, Reform nominee for governor of Florida in 2006, Democratic candidate for Florida's 10th congressional district in 2008 and disqualified candidate for U.S. Senate in 2018 (qualified for the general election as Independent) Bruce Poliquin, former U.S. representative for Maine's 2nd congressional district and former treasurer of Maine

Polling Poll source Date(s)administered Samplesize Marginof error SusanCollins DerekLevasseur UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%55%10%34%

with Susan Collins and Paul LePage Poll source Date(s)administered Samplesize Marginof error SusanCollins PaulLePage UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%29%63%8%

with Susan Collins and Shawn Moody Poll source Date(s)administered Samplesize Marginof error SusanCollins ShawnMoody UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%36%45%18%

with Susan Collins and generic Republican if Collins supported impeaching Trump Poll source Date(s)administered Samplesize Marginof error SusanCollins GenericRepublican UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%35%55%10

with Susan Collins and Derek Levasseur if Collins supported impeaching Trump Poll source Date(s)administered Samplesize Marginof error SusanCollins DerekLevasseur UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%37%24%39%

with Susan Collins and generic Republican Poll source Date(s)administered Samplesize Marginof error SusanCollins GenericRepublican UndecidedPublic Policy Polling (D) October 11–13, 2019 271 (LV) ± 6%53%38%9%

Results

Democratic primary On April 20, 2019, attorney and activist Bre Kidman became the first person to announce their candidacy for the Democratic nomination. If elected, they would have been the first ever non-binary U.S. senator. On June 13, 2019, former Maine gubernatorial candidate Betsy Sweet declared her candidacy. Eleven days later, Maine House Speaker Sara Gideon announced her candidacy, receiving widespread media coverage.Multiple sources: General Jon Treacy had previously announced his candidacy before withdrawing. Former Google executive and political aide Ross LaJeunesse, who would have been the first openly gay man elected to the Senate, announced his candidacy in November 2019. He received the endorsement of the national political group the Victory Fund in January 2020. LaJeunesse withdrew from the race in March 2020, citing the inability to continue his strategy of campaigning in person due to the COVID-19 pandemic, and endorsed Gideon. Two debates were held with all three candidates, while one hosted by WCSH was attended only by Sweet and Kidman.Multiple sources:

Candidates

Nominee Sara Gideon, speaker of the Maine House of Representatives

Eliminated in primary Bre Kidman, attorney, activist, and artist Betsy Sweet, activist, former director of the Maine Women's Lobby, and candidate for governor of Maine in 2018

Withdrawn Michael Bunker, travel agent Christine Gates Ross LaJeunesse, former head of international relations at Google, former aide to George J. Mitchell, Ted Kennedy, Steve Westly and Arnold Schwarzenegger (endorsed Gideon) Cathleen London, physician and member of the Maine Democratic Party State Committee Updated November 11, 2019. Jon Treacy, retired U.S. Air Force major general

Declined Shenna Bellows, state senator and nominee for U.S. Senate in 2014 Seth Berry, state representative (endorsed Gideon) Emily Cain, executive director of EMILY's List, nominee for Maine's 2nd congressional district in 2014 and 2016, former state senator, and former state representative Adam Cote, candidate for Maine's 1st congressional district in 2008 and candidate for governor of Maine in 2018 Matthew Dunlap, Maine secretary of state and candidate for U.S. Senate in 2012 Jared Golden, incumbent U.S. representative for Maine's 2nd congressional district and former state representative James Howaniec, former mayor of Lewiston Stephen King, author (endorsed Gideon) Daniel Kleban, businessman Janet Mills, governor of Maine and former attorney general of Maine Chellie Pingree, incumbent U.S. representative for Maine's 1st congressional district and nominee for the U.S. Senate in 2002 Hannah Pingree, former Speaker of the Maine House of Representatives (endorsed Gideon) Susan Rice, former United States National Security Advisor and former United States Ambassador to the United Nations Cecile Richards, former president of Planned Parenthood Zak Ringelstein, schoolteacher and nominee for U.S. Senate in 2018 (endorsed Sweet) Rosa Scarcelli, businesswoman and candidate for governor of Maine in 2010 Ethan Strimling, former mayor of Portland and candidate for Maine's 1st congressional district in 2008

Polling Poll source Date(s)administered Samplesize Marginof error SaraGideon BetsySweet Other /UndecidedVictory Geek (D) May 13–18, 2020 – (LV) –67%17%17%Colby College/SocialSphere February 10–13, 2020 383 (LV) –60%8%33%

Results

Other candidates Green Independent Party Two candidates declared their intentions to run for the Maine Green Independent Party's nomination, but one withdrew and the other left the party to become an independent. Lisa Savage left the party because of Maine's ballot access requirements; Savage needed 2,000 registered party members to sign a nomination petition to appear on the ballot as the Green Party candidate but could only gather them from January 1 until the March 15 deadline. The Green Party had roughly 41,000 members statewide, which was significantly fewer than the Democratic and Republican parties but nonetheless required the same number of signatures. No alternative party candidate for statewide office had been able to meet this requirement since Pat LaMarche did so in 2006 for governor. Instead, Savage sought to appear as an independent candidate, which required 4,000 signatures, but they may be from any registered voter, not just party members, and they could have been gathered until the June deadline.

Withdrawn