March 17, 2026 / 6:27 AM EDT / CBS News
A bitter Democratic primary is playing out in Maine as two candidates compete for the chance to unseat five-term Republican Sen. Susan Collins, one of the GOP’s most vulnerable incumbents this cycle.
The contest matches centrist Gov. Janet Mills against progressive outsider Graham Platner, an oyster farmer, military veteran and former private military contractor. It also has a generational angle: Mills is 78 and points to her statewide track record, while 41-year-old Platner casts himself as a change candidate.
Polling is sparse, but some recent surveys show Platner leading among Democratic primary voters. Fundraising figures give Platner a financial edge: federal filings show he raised roughly $7.8 million last year, compared with about $2.6 million for Mills and $4.6 million for Collins. Longshot Democrat David Costello has raised just over $21,000, not counting loans. Given the national stakes, outside groups are expected to spend heavily once the contest intensifies.
The race has become increasingly negative. Mills’ campaign this week ran a statewide, six-figure ad buy that highlights controversial posts Platner allegedly made on Reddit, including a 2013 comment suggesting women worried about rape “should not get so f***ed up they wind up having sex with someone they don’t mean to” and should “act like an adult.” CBS News sought comment from Platner’s team. Platner has apologized for many of the posts; in an October video he said readers who saw those remarks were “f***ing embarrassed” and called the posts a product of an earlier part of his life, attributing some of the language to crude military humor and to struggles with depression and PTSD after service in Iraq with the Marine Corps and later in Afghanistan with the National Guard.
Additional reporting last year unearthed other Reddit entries in which Platner allegedly used profanity to describe police, called himself a communist, and posted comments interpreted as disparaging toward rural White people. He also faced scrutiny over a tattoo that resembled a Nazi symbol; Platner has said he got the tattoo during a night of heavy drinking in Croatia nearly two decades ago, has since covered it up, and did not realize at the time that it had Nazi connotations.
Both Democrats have focused much of their public messaging on Collins. Mills, a former district attorney and attorney general who won reelection as governor in 2022 with 55% of the vote over former Gov. Paul LePage, was a top recruit for Senate Democratic Leader Chuck Schumer and has emphasized her record and experience. She gained national attention last year for a public confrontation with former President Trump at a White House event, telling him “See you in court” after he threatened to cut funding to Maine.
Platner has run an insurgent campaign appealing to the progressive and populist wings of the party, arguing Democrats need a more confrontational candidate willing to challenge both Republicans and party leaders. He has framed the primary as a “generational race” pitting “old ideas vs. new ideas.” While Mills has Schumer’s backing, Platner has drawn endorsements from Sen. Bernie Sanders of Vermont, Sen. Ruben Gallego of Arizona, the United Auto Workers and the Maine State Nurses Association.
The primary winner in June will face Collins, who has represented Maine for nearly 30 years and built a reputation as a moderate willing to break with GOP leaders and with Trump. Collins remains a formidable general-election candidate because of deep local ties and a history of winning statewide even when Republican presidential candidates have faltered. Maine leans Democratic — Trump lost the state by about 7 points in 2024 — but flipping Collins’ seat is still a challenging path for Democrats, who must gain multiple GOP seats to secure a Senate majority.
The race’s combination of vulnerability at the Senate level, a high-profile incumbent, sharp intra-party divisions and the unresolved question of who can best defeat Collins has made Maine one of the most closely watched contests this cycle.