Collins vs. Mills: A five-term incumbent against a sitting governor in in Maine — who will set up 2026 midterm race?

One of the most closely watched Senate races has taken shape in Maine as US mid-term elections in 2026 approach, pitting five-term Republican Senator Susan Collins against sitting Democratic Governor Janet Mills. In this contest, both parties see it as central to the battle for control of the chamber. Earlier, Janet Mills suspended her US Senate campaign on April 30, 2026, ending her primary challenge against Susan Collins due to a lack of financial resources and trailing poll numbers.

Collins, in the Senate since 1997, officially launched her bid for a sixth term in February, framing her campaign around experience and independence. She chairs the powerful Senate Appropriations Committee and has long positioned herself as one of the chamber's more moderate Republicans, though Democrats argue she has increasingly aligned with President Trump's agenda.

Also read: Iran has lost ‘complete control’ of Hormuz, US able to ‘provide security’ in Middle East, says Rubio

Mills enters race in October 2025

Mills, Maine's two-term governor and the first woman elected to that office, entered the race in October 2025 after months of public deliberation. Barred from seeking a third term as governor, she framed her Senate run as a stand against Trump, and stated that she won't sit idly by while Maine people suffer and politicians like Susan Collins bend the knee as if this were normal.

The race carries outsized national stakes. Of the 20 Senate seats Republicans are defending in 2026, Maine is the only one in a state Democrats carried in the 2024 presidential election, making it a top Democratic pickup target in their push to retake the Senate majority.

Collins has never lost a Senate race in Maine; her only electoral defeat came in a 1994 gubernatorial bid. She defeated Democrat Sara Gideon by more than 8 points in 2020. But Maine has trended bluer since then, with registered Democrats now outnumbering unenrolled independent voters, a shift that could work against her.

Mills, however, must first navigate a contested Democratic primary. Progressive oysterman Graham Platner has emerged as a serious rival, winning an endorsement from Senator Bernie Sanders and outraising both Mills and Collins in recent fundraising filings. Jordan Wood and Dan Kleban are also running. Sanders has publicly criticised national Democrats for pushing Mills into the race, calling Platner the stronger candidate to beat Collins.