• Governor Janet Mills announces her campaign for the Senate against incumbent Susan Collins.
• Mills faces a competitive primary with progressive candidate Graham Platner.
• The Maine Senate race is now considered a toss-up by analysts.
• Mills has a strong electoral history, having won her last two gubernatorial elections by significant margins.
• Democratic leaders see Mills as a key candidate to flip the seat in 2026.

Maine Governor Janet Mills has officially launched her campaign for the U.S. Senate, aiming to challenge long-serving Republican Senator Susan Collins in what analysts now categorize as a "toss-up" race. Mills, a two-term governor known for her moderate stance and electoral success, has previously won gubernatorial elections by more than seven points, solidifying her popularity among Maine constituents. She stated, "I won't sit idly by while Maine people suffer and politicians like Susan Collins bend the knee as if this were normal," signifying her intent to counter Collins' influence, especially in light of past support for former President Trump’s policies, according to CBS News.

Mills enters a Democratic primary that includes influential candidates like Graham Platner, an oyster farmer and military veteran endorsed by Senator Bernie Sanders. Platner is presenting himself as a working-class advocate, aiming to leverage grassroots support gained from raising significant funds—over $4 million in just a few months. This dynamic could complicate Mills' path to the nomination, as progressive voices within the party express skepticism about the establishment’s push towards her candidacy, according to ABC News, HuffPost, and Reuters.

Analysts have noted that the ratings for the Maine Senate race have shifted due to Mills' candidacy, with the Cook Political Report now considering it a toss-up, marking a significant change from a "lean Republican" designation. Collins, who has held her Senate seat since 1997, must now contend with a candidate who has long been viewed as a strong recruiter for national Democrats. However, Mills will need to navigate her primary battle while continuing to focus on presenting herself as a viable alternative to Collins, especially as the political climate becomes more polarized, according to The Hill.

Mills has characterized her candidacy as essential to counteract the impact of Trump's policies on Maine, recalling a past incident where he threatened federal funding over the state’s transgender athlete policies. "If this President and this Congress were doing things that were even remotely acceptable, I wouldn't be running for the U.S. Senate," Mills asserts in her launch video, as reported by HuffPost and Reuters.

Collins, who has historically faced challenges during elections but has avoided defeat, will now face a more vigorous campaign from Mills, who has a compelling narrative emphasizing her fight against established power. Collins' experience and popularity may yet present significant hurdles in an increasingly changing political environment, reflecting a critical race for control of the Senate as the 2026 elections approach, according to CBS News and The Hill.