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. 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. 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). 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==