Maine: Can Susan Collins survive another Democratic challenge?

Why it is a battleground: Maine is unusual in the Senate map. Collins is a Republican representing a state that Kamala Harris carried by about 6.9 percentage points in 2024. She has won statewide by building an independent image, but that image is under pressure as national partisanship becomes stronger. Maine voters have supported Collins while also backing Democratic presidential candidates, creating a split-ticket environment that makes the contest competitive.

Key players: Collins has served in the Senate since 1997 and has built a reputation for working across party lines, although she has also supported many Republican priorities and Trump administration nominations. Graham Platner is a Democratic candidate with backing from progressive activists and national Democrats. His challenge is to connect the race to healthcare, affordability and the direction of the Republican Party without allowing Collins to make the contest solely about her individual record.

What to watch: Healthcare, abortion rights, tariffs, energy prices and Collins’ relationship with Trump will be important. Watch whether Platner can consolidate Democrats and appeal to independent voters. Collins will need to preserve support among moderates while keeping Republican voters engaged. Maine’s preference for ranked-choice voting in federal races may also make the campaign’s coalition-building and second-choice appeal significant.

Last election: Harris carried Maine in the 2024 presidential election, while Collins remained the state’s Republican senator. Collins last won re-election in 2020. Her ability to outperform the Republican presidential ticket is the central historical fact behind the race, but Democrats believe the state’s current political alignment gives them a stronger opening than in earlier cycles.

The wider stakes: Maine could decide whether Democrats are able to assemble a Senate majority without winning every major Republican target. Collins’ defeat would also mark a sharp change in the state’s long-running pattern of electing a moderate Republican senator. If she survives, Republicans will point to Maine as evidence that candidate identity can still overcome a state’s presidential voting pattern.

Campaign dynamics: The contest will reward a candidate who can hold a broad coalition. Collins needs Democrats and independents who value her experience, while Platner needs to make the race feel like a choice about national direction. National groups will try to define both candidates early. Local endorsements, debates and the candidates’ responses to Trump-related issues will receive close attention.