Troy Jackson (D) defeated incumbent Sen. Susan Collins (R) and six other candidates in the general election for the U.S. Senate in Maine on November 3, 2026. Click here for detailed results. Collins' defeat made her the first U.S. Senator to lose a bid for a sixth term since William Roth (R-Del.) in 2000.

On July 25, 2026, Jackson won the nominating convention to become the Democratic nominee, marking the 28th time since 1918 that a new candidate was selected to replace a U.S. Senate nominee. The nominating convention became necessary after Graham Platner (D), the winner of the 2026 Democratic primary for the U.S. Senate in Maine, withdrew from the general election on July 10, 2026, following an allegation of sexual assault.

According to the Portland Press Herald's Randy Billings, Republicans tried to tie Jackson with Platner, saying Jackson is "'Graham Platner 2.0,' only he embodies many of the bad traits that sank the former oyster farmer's candidacy for U.S. Senate — and none of the qualities that drew record support in the primary." Billings wrote that, on the other hand, Democrats tried to cast Collins as "a 'rubber stamp' for President Donald Trump, whose judicial appointments are taking rights away from women and whose policies are making life for the working class harder while the rich get richer."

This U.S. Senate seat was the only one Republicans were defending in a state that Kamala Harris (D) won in the 2024 presidential election. Harris defeated President Donald Trump (R) in the state 52.4% to 45.5%. Politico's Jessica Piper and Aaron Phellish wrote that "[Collins'] bid will rely on a coalition that includes independents and Democrats, many of whom have backed her in the past because of her breaks from Trump and other GOP leaders."

Collins was first elected to the U.S. Senate in 1996. She previously served as commissioner of the Maine Department of Professional and Financial Regulation, New England regional director of the U.S. Small Business Administration, and deputy state treasurer of Massachusetts.

Collins ran on her experience in the U.S. Senate and as chair of the chamber's Appropriations Committee. According to her campaign website: "This committee decides how federal dollars are spent each year, from national defense and infrastructure to medical research, education, and public safety. Susan's position gives Maine an outsized voice at the table when critical decisions are made which allows her to deliver serious results for Maine."

Jackson served in the Maine Senate from 2008 to 2014 and from 2016 to 2024. During his tenure in the chamber, Jackson served as Democratic leader and Senate President. Jackson previously served in the Maine House of Representatives from 2002 to 2008 and worked as a logger.

Jackson ran on a message of economic populism. In his Candidate Connection survey response, Jackson wrote, "Now Mainers need someone fighting for them more than ever. Susan Collins has spent thirty years in Washington and has more power than ever, but she keeps siding with Donald Trump and the billionaires instead of using that power for Maine. I'm running because Maine deserves a senator who will show up, stand up, and fight like hell for working people."

Both Collins and Jackson were from Aroostook County, Maine. According to The Cook Political Report's Jessica Taylor, this election was the first in which Collins faced a challenger from northern Maine: "It's a regional advantage that Collins, who is from the town of Caribou, has long held. All of Collins' previous opponents — including the 2020 nominee, House Speaker Sara Gideon — came from southern Maine and were not seen as authentically 'Maine' enough. Jackson won't have that problem."

Based on third-quarter reports filed with the Federal Election Commission (FEC), Collins raised $25.2 million and spent $23.8 million, and Jackson raised $26.9 million and spent $25.3 million. To review all the campaign finance figures in full detail, click here.

Sigrid Ann Olson (D) (Write-in), Ashley Webb (D) (Write-in), Joseph Steinberger (Faith in Humanity Party) (Write-in), Brent Andrews(Unaffiliated) (Write-in), Michael Turcotte (Unenrolled) (Write-in), and Gina Oswald (Independent) (Write-in) also ran.

As of Oct. 27, 2026, The Cook Political Report, DDHQ/The Hill, Inside Elections, and Sabato's Crystal Ball rated the general election as a Toss-up.