By Chris Wade
The Center Square

Maine’s Democratic Gov. Janet Mills is expected to announce a bid for the U.S. Senate with a challenge to Republican Sen. Susan Collins in next year’s election.

Mills, 77, is expected to announce her candidacy on Tuesday, becoming the highest-profile Democrat to challenge the incumbent lawmaker, who is seeking a sixth term. The two-term governor and former attorney general, who is prevented from seeking another term, is viewed by top Democrats, including Senate Minority Leader Chuck Schumer, as the best shot for unseating the veteran GOP senator.

Mills’ campaign briefly posted a video announcement on social media about the U.S. Senate bid on Friday, vowing to “flip Maine’s Senate seat blue”, but it was taken down several hours later. A link on the now-deleted post directed supporters to an ActBlue fundraising page, which has also been removed.

“I’ve spent my career standing up for Maine families as a prosecutor, Attorney General, and Governor,” Mills said in a statement on the ActBlue page, boasting of her political experience. “I’ve taken on Big Pharma and expanded healthcare access, and took Donald Trump to court — and won.”

Several media outlets reported that Mills will be making a formal announcement on Tuesday, but it wasn’t clear when that would happen. There was no comment from her campaign.

Mills has raised her national profile over the past several months in a public feud with President Donald Trump over his divisive policies, including the White House’s push to block states from allowing transgender athletes to compete in women’s sports. The Democrat has refused to comply with Trump’s transgender directives, telling the president during a recent meeting of governors: “See you in court.”

Before she can take on Collins, however, Mills would face an already crowded field of Democrats who’ve announced their campaigns, including Marine veteran and oyster farmer Graham Platner, former congressional staffer and End Citizens United vice president Jordan Wood, and businessman Dan Kleban.

Platner, who jumped into the race in August, has won support from Democratic Vermont Sen. Bernie Sanders, who argues that the political newcomer is the party’s best shot at defeating Collins next year and regaining control of the U.S. Senate. Sanders has criticized fellow Democrats for encouraging Mills to run.

“It’s disappointing that some Democratic leaders are urging Governor Mills to run,” Sanders posted on social media. “We need to focus on winning that seat & not waste millions on an unnecessary & divisive primary.”

To be sure, Collins remains popular among a broad cross-section of Maine voters, including independents. The moderate Republican was first elected to the Senate in 1996 and has been handily reelected every term since then despite opposition. In the 2020 election, Collins was reelected by nearly 9 points in the blue state, even as then-Democratic presidential candidate Joe Biden carried the state by a similar margin.