Maine Gov. Janet Mills kicks off Senate run in critical 2026 race

The first woman to be elected governor of Maine is set to try and accomplish what no candidate in her state has managed in more than 30 years: to defeat Republican Susan Collins. 

But to even have the chance to do so, Democrat Janet Mills will first have to make it through what is already primed to be a contentious Senate primary between establishment voices and progressives at a crucial time in her party.

Mills announced on Tuesday she will run in Maine's 2026 Senate contest, offering Democrats one route to try to unseat the longtime GOP incumbent Collins and thin out the Republican Senate majority in Washington. 

"I won't sit idly by while Maine people suffer and politicians like Susan Collins bend the knee as if this were normal," Mills said in an announcement video posted early Tuesday. "My life's work has prepared me for this fight, and I'm ready to win. This election will be a simple choice: Is Maine going to bow down or stand up? I know my answer." 

CBS News reported last week that Mills was expected to launch her campaign on Tuesday. 

The 77-year-old governor has been viewed as a key recruiting target for national Democrats, who face long odds of flipping control of the Senate back next year given a difficult map of races. Mills was first elected governor after winning by more than seven points in 2018, and she won reelection by a 13-point margin four years later.

But recent political history, both locally and across the country, may upend expectations about how Mills will fare in what could become one of the tensest contests of the 2026 midterms. 

Collins has served as one of Maine's senators since 1997, establishing herself as a key moderate Republican voice, albeit one who tends to frustrate members of both major parties at times. During the 2020 presidential election, defeating Collins was a major, and well-funded, priority for Democrats. But Collins still managed to win re-election by more than eight points, even as Democrat Joe Biden's statewide margin over President Trump in Maine was nine points.

The 72-year-old Collins has never lost a Senate race in Maine, her last defeat coming in a run for governor back in 1994. 

Mills' expected entry into the Senate race is already being met with some dismissiveness on the progressive side. Vermont Sen. Bernie Sanders, who is an independent but caucuses with Democrats, is rallying around Graham Platner, a younger first-time statewide candidate who is already in the Senate race and, according to his online campaign bio, is a military veteran and oyster farmer. 

"Graham Platner is a great working class candidate for Senate in Maine who will defeat Susan Collins," Sanders said recently on social media. "It's disappointing that some Democratic leaders are urging Governor Mills to run. We need to focus on winning that seat & not waste millions on an unnecessary & divisive primary." 

In the fallout from a difficult 2024 election cycle where Democrats lost the presidency and Senate, and failed to retake control of the House, there have been persistent questions about how the party can recover. One tension rippling through the party is the subject of generational change, and whether to eschew the older candidates closer in age to Biden, 82, and instead nominate people who can try to revive a Democratic brand that has suffered in recent years. 

With Mills' entry into the race on Tuesday, Democrats in Maine may be on a collision course over those national concerns already rippling through other contests where the party's future direction could be at stake. 

Fin Daniel Gómez contributed to this report.