Maine Gov. Janet Mills has announced her candidacy for U.S. Senate against incumbent Susan Collins (R) in 2026. In her launch video, Mills said, “I won’t sit idly by while Maine people suffer and politicians like Susan Collins bend the knee as if this were normal.” Mills is finishing her second term as governor. She was re-elected in 2022 with 56% of the vote.

Mills is the second governor to announce a candidacy for U.S. Senate after former North Carolina Gov. Roy Cooper (D) announced his bid in July. Ballotpedia covers the results of former and incumbent governors running for U.S. Senate, dating back to 1914, when the 17th Amendment provided for the direct election of U.S. Senators.

During that time period, Nebraska had the most governors who ran for the Senate, with 16. However, Maine ties with Kansas and North Dakota as the state with the fourth-highest number of governors who have run for the Senate, with each having 11 governors who have run for the Senate. The most recent of these governors to run was Angus King (I), who won his election in 2012 and won a third term last year. Additionally, Mills is the second governor to run against Susan Collins after Joseph Brennan (D), whom Collins defeated to win her first term in 1996.

Across 15 elections, including instances of governors running more than once, running concurrently in a special and regular election, or multiple governors running in one election, the most common outcome for Maine governors running for Senate was a defeat in the primary election, which happened six times, the most recent of which was 1948, when Horace Hildreth (R) and Sumner Sewall (R) lost to Margaret Chase Smith (R). The next most common outcome was a victory, which happened five times, the most recent of which was Angus King (I) in 2012. The least common outcome was a general election loss, which most recently occurred when Joseph Brennan (D) lost to Susan Collins (R) in 1996. In total, a Maine governor has been elected 33% of the time, which ties with six other states with a similar victory percentage.

In addition to Mills, eight other Democrats are running for the nomination, including Graham Platner, and Jordan Wood. As of October 14, 2025, The Cook Political Report with Amy Walter ranks this race as “Lean Republican”. To read more about Maine’s 2026 Senate election, click here. To see Ballotpedia’s full database of governors running for Senate, click here.