The 2026 United States Senate election in Maine was held on November 3, 2026, to elect a member of the United States Senate to represent the state of Maine. Democratic former state Senate president Troy Jackson defeated Republican incumbent Susan Collins. The election was conducted with ranked-choice voting.
Primary elections were held on June 9. Collins, seeking a sixth term, was the only candidate to qualify for the Republican nomination. Sullivan harbor master Graham Platner won the Democratic primary over Governor Janet Mills with the support of progressive figures, but withdrew on July 10 amid accusations of sexual assault and other controversies. A party convention selected Jackson to replace Platner as the Democratic nominee on July 25.
This was the only Republican-held seat in a state President Donald Trump lost in the 2024 election. Although Jackson frequently led in polling, onlookers were cautious in anticipating a flip due to Collins having outperformed polls in the 2020 Senate election. Jackson is the first Democrat to win a Senate election in Maine since 1988, while Collins is Maine's first incumbent senator to lose re-election since 1978. Democrats won this seat for the first time since 1972. Collins' loss additionally marks the first time since the party's founding in 1854 that New England will have no Republicans representing the region in the U.S. Senate.
Background
The election was held on November 3, 2026, coinciding with U.S. House elections, a gubernatorial election, and other local elections. Both the primary and general elections were conducted with ranked-choice voting. Incumbent Republican U.S. senator Susan Collins ran for re-election to a sixth term. Both primary elections took place on June 9, 2026. The northernmost state in New England, Maine is considered to be a moderately blue state. Maine has voted for every Democratic presidential nominee since 1992, and Democratic nominee Kamala Harris defeated Republican nominee Donald Trump by approximately seven percentage points in the 2024 United States presidential election in Maine. Democrats also control the governorship, the state legislature, and both seats in Maine's U.S. House congressional delegation. Since 2018, Collins has been the only Republican representing any New England state in either chamber of Congress.
Collins was first elected in 1996. She has been re-elected in four subsequent elections, significantly outperforming other Republicans in the state. In 2020, despite almost all polls and analysts predicting that she would lose her re-election bid, Collins defeated Democratic nominee Sara Gideon by a nine-point margin. Democratic presidential nominee Joe Biden carried Maine by about nine percentage points on the same ballot. This election was expected to be among the most competitive Senate races in 2026. Collins is the only Republican senator who represents one of the 19 states that Donald Trump did not win in any of his three presidential campaigns. With the decline of ticket splitting, Collins was widely viewed as one of the most vulnerable incumbent Republican senators in 2026. Collins was also the only Republican senator facing re-election in a state that Kamala Harris won in the 2024 presidential election. Since the 2024 United States Senate elections, Collins has been the last senator to represent a non-swing state (in other words, a reliably Democratic or Republican state) that typically supports the opposing party.
Republican primary
Incumbent U.S. senator Susan Collins officially announced her re-election bid in February 2026. Despite Collins receiving backlash from some Republicans for not supporting all of Trump's agenda during his second term as president, the Republican Party nonetheless supports her re-election campaign due to the fact that she is the only Republican who has been electorally successful in Maine in recent years. However, she faced an unsuccessful primary challenge from former police officer Dan Smeriglio, who argued that she votes with Senate Democrats too often. Ultimately, Collins was the only Republican to qualify for the primary ballot.
Candidates
Nominee
- Susan Collins, incumbent U.S. senator (1997–present)
Withdrawn
- Carmen Calabrese, restaurant owner
- Bill Clarke, entrepreneur and Constitution Party nominee for U.S. Senate in 1996 and for governor in 1998
- Dan Smeriglio, former police officer
Endorsements
Susan Collins
Fundraising
Italics indicate a withdrawn candidate
According to Federal Election Commission (FEC) records as of October 2026, Collins has received $4,525,846 from political action committees (PACs) affiliated with pro-Israel lobbies; of this amount, $3,670,038 is attributed to the 2026 election cycle.
Democratic primary
In April 2025, former congressional staffer Jordan Wood became the first Democrat to enter the race, running on a platform opposed to the Trump administration and Elon Musk. On August 19, Sullivan harbor master Graham Platner launched a progressive campaign backed by Bernie Sanders and organized labor, positioning himself against the "Democratic establishment" and drawing support from both liberal voters and some 2024 Trump voters. In February 2026, Politico described Platner as "unlike any other recent popular candidate the state has seen". Noting Platner's large social media following, Politico added: "He is brash. He is progressive. He has drawn crowds of hundreds of people, national attention and millions in campaign dollars."
After weeks of speculation and leaked campaign plans, Governor Janet Mills entered the race in October 2025. The DSCC's close involvement in her campaign prompted backlash and allegations of favoritism in the primary. Mills was widely viewed as a top Democratic recruit; she was encouraged to run by Senate Minority Leader Chuck Schumer, Senator Kirsten Gillibrand, and the Democratic Senatorial Campaign Committee (DSCC), although Sanders publicly discouraged her candidacy. Following Mills's entry, several candidates, including Dan Kleban and Daira Smith-Rodriguez, withdrew and endorsed Mills. Smith-Rodriguez cited concerns over past comments by Platner regarding sexual assault in the military. Wood later withdrew to run for the U.S. House.
In January 2026, Platner briefly paused his campaign due to his wife's medical treatment abroad before resuming later that month. He returned to the campaign trail with protests against Immigrations and Customs Enforcement (ICE) actions. In February 2026, Mills committed to multiple debates ahead of the June 9 primary. Mills, Platner, and 2024 nominee David Costello qualified for the primary ballot. In addition, University of Maine adjunct professor Andrea LaFlamme started a write-in bid for the Democratic nomination. The Platner/Mills contest was seen as a key contest between the Democratic Party's centrist establishment wing and the populist, left-wing, and progressive faction, with Mills representing the former and Platner representing the latter.
In March 2026, Mills began running attack ads highlighting Platner's controversies. By April 2026, multiple polls had been released which showed Mills as much as 38 points behind Platner in the primary. Shortly thereafter, the Mills campaign stopped running the attack ads and had made no additional ad purchases across any platform, leading to rumors that she would withdraw from the race. On April 30, Mills announced that she was suspending her campaign, but she did not endorse Platner. Her withdrawal led to Schumer and Gillibrand announcing they would now help Platner to defeat Susan Collins. Following the end of Mills' campaign, Platner was the only prominent and competitive Democrat left in the race, making him the most likely Democratic nominee. Mills' name remained on the primary ballot, and Costello also continued his campaign. On June 9, Platner won the primary; he received over 150,000 votes, more than any other Democratic candidate in a primary in Maine's history.
Platner misconduct controversies
Shortly after Mills entered the race, Platner came under fire for resurfaced controversial Reddit posts criticizing police officers, calling rural Americans "stupid" and referring to himself as a "communist", resulting in his campaign's political director, former state representative Genevieve McDonald, quitting the campaign and calling Platner "unelectable"; however, Democratic National Committee Chair Ken Martin stated that the comments were not disqualifying, and Platner apologized in a five-minute video posted to social media. On October 21, Platner released a video of himself dancing and singing shirtless at his brother's wedding, revealing he had a chest tattoo that resembled the Totenkopf used by Nazi Germany's Schutzstaffel. Platner stated he got the tattoo while inebriated with other U.S. Marines while stationed in Croatia, mistaking the symbol for a generic skull and crossbones. He had the tattoo covered, and professed his shame and disgust for getting a tattoo that resembled the fascist insignia. Platner also called himself an anti-fascist "supersoldier" in an old Reddit comment.
After the controversies, Democrats such as Senator Chris Murphy defended Platner and said that he "sounds like a human being" who is honest about his mistakes. Senator Ruben Gallego called his campaign "authentic" and said that he has "the right to grow out of his stupidity" and is not going to be a "crypto-Fetterman". On February 26, 2026, Platner quote-tweeted a clip from Donald Trump's 2026 State of the Union Address, criticizing Trump's speech. The clip had been posted by anti-Semitic white supremacist Stew Peters. The tweet was deleted hours later, with a spokesperson for Platner's campaign telling The Hill that they were unaware of Peters's views.
In May 2026, reports surfaced that Platner's wife had alerted his campaign team to explicit messages he was sending to women on the messaging app Kik, expressing concern that the behavior could hurt him politically. Additional reports during the same period drew attention to Platner's Nazi-linked tattoos, as well as past social media posts widely described as bigoted. In June 2026, The New York Times published an article including allegations of physical abuse and "unsettling" behavior from multiple women. In response, Platner told media that his poor behavior was attributed to PTSD from his service in the Marine Corps. While he specifically denied the accusations made by one woman, he did not dispute the characterization of his behavior toward a second one.
Candidates
Withdrew after nomination
- Graham Platner, Sullivan harbor master
Eliminated in primary
- David Costello, former deputy secretary of the Maryland Department of the Environment and nominee for U.S. Senate in 2024
- Andrea LaFlamme, adjunct professor at the University of Maine (write-in candidate)
- Janet Mills, governor of Maine (2019–present) (suspended campaign)
Withdrawn
- Natasha Alcala, fashion designer
- David Evans, former Department of Defense policy writer
- Tucker Favreau, cybersecurity professional
- Dan Kleban, brewery owner (endorsed Mills)
- Daira Smith-Rodriguez, former civilian contracting officer for the U.S. Air Force (endorsed Mills)
- Jordan Wood, former chief of staff to former U.S. Representative Katie Porter (ran for U.S. House; endorsed Platner)
Declined
- Aaron Frey, Maine attorney general (2019–present) (endorsed Mills)
- Jared Golden, U.S. representative from Maine's 2nd congressional district (2019–present)
- Chellie Pingree, U.S. representative from Maine's 1st congressional district (2009–present) and nominee for U.S. Senate in 2002 (running for re-election)
Endorsements
Graham Platner
Executive branch officials
- Robert Reich, former U.S. secretary of labor (1993–1997) (endorsement rescinded after primary)
- Nirav D. Shah, former principal deputy director of the Centers for Disease Control and Prevention (2023–2025) and 2026 gubernatorial candidate (endorsement rescinded after primary)
- Ruben Gallego, Arizona (2025–present) (endorsement rescinded after primary)
- Kirsten Gillibrand, New York (2010–present) (previously endorsed Mills, endorsement rescinded after primary)
- Martin Heinrich, New Mexico (2013–present) (endorsement rescinded after primary)
- Chris Murphy, Connecticut (2013–present) (endorsement rescinded after primary)
- Bernie Sanders, Vermont (2007–present) (Independent) (endorsement rescinded after primary)
- Brian Schatz, Hawaii (2012–present) (endorsement rescinded after primary)
- Chuck Schumer, Senate Minority Leader (2017–2021, 2025–present) from New York (1999–present) (previously endorsed Mills, endorsement rescinded after primary)
- Tina Smith, Minnesota (2018–present) (endorsement rescinded after primary)
- Elizabeth Warren, Massachusetts (2013–present) (endorsement rescinded after primary)
- Sheldon Whitehouse, Rhode Island (2007–present) (endorsement rescinded after primary)
- Ro Khanna, CA-17 (2017–present) (endorsement rescinded after primary; endorsed Jackson)
- Shenna Bellows, Maine secretary of state (2021–present) and 2026 gubernatorial candidate (endorsement rescinded after primary)
- Matthew Dunlap, Maine state auditor (2021; 2022–present), former Maine secretary of state (2005–2011; 2013–2021), and 2026 candidate for ME-02 (endorsement rescinded after primary)
- Tim Walz, governor of Minnesota (2019–present) (endorsement rescinded after primary)