Graham Platner, a Marine Corps veteran and oyster farmer, won Maine’s Democratic primary on June 9, 2026, securing the party’s nomination to challenge Republican incumbent Susan Collins in a race that will help determine control of the U.S. Senate.
Platner captured 77.7% of the vote, according to the Bangor Daily News and Decision Desk HQ, decisively defeating former Gov. Janet Mills, who suspended her campaign in April after Platner built early fundraising momentum. Former government official David Costello received 5.6%.
The victory sets up one of the country’s most closely watched Senate contests. Collins, a five-term Republican who has held the seat since 1997, is the longest-serving Republican woman in Senate history and is also her party’s most vulnerable incumbent this year, according to The New York Times. Maine voted for Vice President Kamala Harris in 2024, making the state a prime target for Democrats.
Platner, 41, has drawn national attention for his insurgent campaign despite facing multiple controversies. The Bangor Daily News reported that he sent sexually explicit messages to several women early in his marriage and was accused by ex-girlfriends of toxic behavior. He has also faced criticism over a Nazi-linked tattoo he later covered and old offensive social media posts. Platner has apologized for his Reddit posts, denied allegations of violence in past relationships, and framed his campaign around his own growth after struggling with post-traumatic stress disorder.
In recent polling, Platner holds a lead over Collins. A UMass Lowell poll from early June showed Platner with a slight advantage in a general election matchup. Real Clear Polling’s average of recent polls showed Platner at 48.7% to Collins’ 41.3%, a 7.4-point lead.
The general election will test whether Platner’s grassroots support can withstand an unprecedented advertising blitz. More than $150 million in advertising time has been reserved for the race, according to AdImpact data—already exceeding the $120 million spent during Collins’ record-setting 2020 reelection. Of that total, $100 million has come from Republican sources. Pro-Collins groups released ads on primary night featuring Platner’s offensive social media posts.
Platner’s campaign centers on progressive priorities including Medicare for All, a billionaires tax, immigration reform, and ending what he calls “forever wars.” He has criticized Collins as part of a corrupt system beholden to corporate donors. Some establishment Democrats, including U.S. Rep. Josh Gottheimer of New Jersey, have called for him to withdraw, but prominent progressives such as U.S. Sens. Bernie Sanders and Elizabeth Warren have not abandoned the race.
The November 3 general election will occur as Republicans hold a 53-45 majority in the Senate. Collins is one of only a handful of Republican senators representing states that lean Democratic, making her seat a key battleground for Senate control.
Sources
- Bangor Daily News — primary results, Platner’s vote share, controversies, and general election setup
- The New York Times — Collins’ status as most vulnerable Republican incumbent, Maine’s 2024 voting pattern
- UMass Lowell — general election polling showing Platner with slight lead over Collins
- Real Clear Polling — polling average showing Platner leading Collins 48.7% to 41.3%
- Wikipedia — Platner’s background as Marine Corps veteran and oyster farmer; November 3, 2026 general election date
- The Guardian — Collins’ 30 years in Senate; Platner as marine veteran and oysterman
