Maine Senate race odds and predictions 2026

Last updated: October 16, 2026

News and updates (as of October 16, 2026):

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The Maine Senate race is one of the most closely watched contests of the 2026 midterms. Sen. Susan Collins is the only Republican senator on the ballot this year in a state Kamala Harris won in 2024, and Democrats likely need her seat to reach the net gain of four they need for control of the Senate.

The Democratic side of the race changed in the middle of the summer. Graham Platner won the June primary but dropped out in July after a sexual assault allegation, which he denied. Maine Democrats then chose former state Senate President Troy Jackson as their nominee at a July 25 convention in Bangor.

Three kinds of forecasts track the race, and they measure different things. Polls are a snapshot of voters at one moment, with a margin of error. Kalshi prices show what traders are willing to pay right now. Race ratings are analysts' judgments in broad categories. Right now, polls show Jackson narrowly ahead within the margin of error, Kalshi prices him as a modest favorite, and Cook Political Report calls the race a Toss Up. Here's who is running, what the Maine Senate odds show, and what could decide the race.

For key dates, registration deadlines and prediction market odds heading into Election Day, see Kalshi's guide to when the 2026 midterm elections are.

Two candidates are on the November ballot for Senate in Maine: Republican Sen. Susan Collins and Democrat Troy Jackson.

Write-in candidates: Six people filed as declared write-in candidates, and none are registered Republicans: Brent Andrews (unaffiliated), Sigrid Ann Olson (Democrat), Gina Oswald (independent), Joseph Steinberger ("Faith in Humanity"), Mike Turcotte (unenrolled) and Ashley Webb (Democrat). Their names don't appear on the ballot, but voters can write one in on a third line. A write-in vote for someone who didn't declare isn't counted.

Ranked-choice voting: Because there are declared write-ins, the race uses a ranked-choice ballot. Maine uses ranked-choice voting for federal general elections, but not for governor. If no candidate wins more than 50% of first-choice votes, the last-place candidate is eliminated and those ballots move to their next choice until someone has a majority. That central count happens in Augusta and can take days. In 2020, Collins won outright in the first round with 51%.

The Maine Senate primary was held on June 9, 2026. Platner won the Democratic primary with 72.3%, ahead of Gov. Janet Mills at 19.4% and David Costello at 8.3%. Mills had suspended her campaign in April but stayed on the ballot. Collins was the only Republican on the primary ballot.

A sexual assault allegation against Platner surfaced about a month after the primary. Jackson, who had finished third in the governor's primary the same day, joined the Democrats calling on Platner to step aside. After Platner withdrew, about 600 delegates nominated Jackson at the party convention. Collins' campaign has argued Jackson was handpicked by party insiders.

2026 Maine Senate race schedule

As of October 16, 2026, Kalshi traders price Troy Jackson at 57% and Susan Collins at 43% to win the Maine Senate race. If you're asking who will win the Maine Senate race, the market's current answer is Jackson as a modest favorite, with Collins still holding a real chance. These Maine Senate odds can change quickly before Election Day.

Kalshi's "Maine Senate winner?" market resolves by winning party. Each candidate has one binary yes/no contract, priced continuously in cents from 1 to 99 based on live trading. If that candidate's party wins the seat, the contract pays $1; if not, it pays $0. That means a candidate priced at 57 cents is trading at roughly a 57% market-implied chance of winning.

Here's how that works with the live prices as of writing:

Maine Senate winner market. Prices as of October 16, 2026 2:39pm ET

Market volume: $12.9 million. Market prices reflect current trading, not a guaranteed result. Kalshi's separate Maine Senate margin of victory market forecasts a Democratic margin of about 1.1 points.

Jackson, a former logger and state Senate president, is the favorite on Kalshi at 57%. He has led most public polls since he entered the race, and he leads narrowly in Kalshi's polling average, 49% to 47.1%. A Washington Post-Schar School poll of 800 likely voters, taken September 30 to October 5, had him ahead 50% to 46%, with a 13-point lead among independents.

Jackson also has a big fundraising edge. He raised $20.4 million in his first three months in the race, four times what Collins raised, and his campaign said nearly 95% of contributions were under $100. But he spent $16.5 million of it, ending September with about $4 million in cash and roughly $1 million in debt. On the trail and in the debates, Jackson has tied Collins to President Trump, high prices, tariffs on Canada and the war in Iran. He has also pressed her over a ProPublica report on illegal 2020 donations to a pro-Collins super PAC.

His price has come down from its peak. In late September, Collins traded as low as 27%. A New York Times/Siena poll showing her ahead 49% to 46% then pushed her price up, and Jackson fell to 62%. He has traded between about 56% and 60% since the first debate on October 6.

Collins, first elected in 1996, is priced at 43%. She has a record of beating her polls. In 2020, she trailed in nearly every public poll but won 51% to Sara Gideon's 42.4%, while Joe Biden carried Maine by about 9 points. Kalshi has a separate market on whether Collins will outperform the polls again this year.

Collins, first elected in 1996, is priced at 43%. She has a record of beating her polls. In 2020, she trailed in nearly every public poll but won 51% to Sara Gideon's 42.4%, while Joe Biden carried Maine by about 9 points. Kalshi has a separate market on whether Collins will outperform the polls again this year.

LV = likely voters, RV = registered voters. Sources: RealClearPolling, Marist, Washington Post, CBS News, AARP.

Three swing factors will likely decide the race: how many voters split their tickets, which side's voters turn out, and where the few remaining undecided voters land. Collins' path depends on running ahead of national Republicans with independents and older voters. Jackson's depends on Maine voting the way it has in recent federal races.

The split-ticket gap is already visible. In the same AARP poll that had Jackson up 3 points, Democrat Hannah Pingree led the governor's race by 13. A CBS News/YouGov poll found Collins winning about one in five voters who disapprove of Trump. Few voters are left to persuade: 3% were undecided in the AARP poll and 4% in Suffolk's.

The two candidates draw on different generations. The AARP poll found Jackson ahead by 25 points among voters under 50, while Collins led 53% to 44% among voters 50 and older. She won 70% of older swing voters who don't vote a straight party line.

That matters because older voters are the more reliable midterm voters, and Maine has the highest share of residents 65 and older of any state. In the AARP poll, 87% of voters 50 and older said they were extremely motivated to vote, compared with 73% of voters under 50. Geography splits the same way: Suffolk found Jackson ahead on the South Coast and Mid Coast, while Collins led in East Maine and the rural North.

Maine leans Democratic in federal races, which is what makes Collins' seat a target. Harris carried the state by about 7 points in 2024, and Biden carried it by about 9 in 2020. Marist found Democrats with a 9-point lead on the generic congressional ballot.

But Maine has a long record of splitting its tickets. Democrats haven't won a Senate race in Maine since 1988, and Collins won all 4 of her reelections, including 2020, when she beat her polls on the same ballot Biden won. In a Washington Post-Schar School poll, 55% of likely voters said they want Democrats to win the Senate, but the Senate race itself was within the margin of error.

The money is split in an unusual way. Jackson has outraised Collins about four-to-one since he entered the race, mostly from small donors through ActBlue, and he has support from Sen. Bernie Sanders and several labor PACs. Collins has more cash in the bank, contributions from national Republicans including former President George W. Bush, and much heavier outside ad support.

Both sides are spending on the closing argument. A Democratic super PAC, WinSenate, put $3.4 million into ads about the ProPublica report. Collins' campaign has dismissed the report as a political hit job, and Republicans have cast Jackson as too far left for Maine.

This race has already been reset once. Jackson has been the nominee for less than three months, and his first fundraising report only came out on October 15, minutes before the final debate. The ProPublica story, which Collins disputes, broke in September, and a group of more than 250 Mainers has since asked the state attorney general to investigate.

The four debates are now over, and the last one turned testy. When a protester interrupted, Collins suggested the protester was a Jackson supporter, and Jackson told her to "shut up." With early voting underway and ranked-choice tabulation possible if neither candidate clears 50%, the final result may not be known on election night.

Two takeaways stand out in the Maine Senate race. First, Kalshi's market prices Jackson as a modest favorite at 57%, as of October 16, 2026, down from 62% in late September. Second, polls show a race within the margin of error, and Collins' strength with older voters is the main counterweight to a challenger who leads overall.

That makes Maine one of the races to watch on election night, and one that could help decide control of the Senate. If no one clears 50%, ranked-choice tabulation could push the final call past November 3.

To follow how the odds move through Election Day, track the live Maine Senate market on Kalshi and the rest of the 2026 Senate markets, including Kalshi's Democratic Senate control and Republican Senate control markets. For the full Senate picture, see Kalshi's 2026 Senate election guide, who will control the Senate in 2026, 2026 midterm predictions, and the Texas Senate race odds.

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