AUGUSTA, Maine — What began as a scramble to find a strong Democratic challenger to Republican Sen. Susan Collins has escalated into a bruising, expensive primary between Gov. Janet Mills and Graham Platner, a veteran-turned-oyster farmer, even as Collins herself has spent little on her own reelection so far.
The primary, with the June 9 vote more than two months away, matters for Democrats’ long-shot bid to flip the U.S. Senate. It has developed into a proxy fight between the party establishment and an insurgent wing, while outside Republican groups pour resources into protecting Collins and her bid for a sixth term.
Two competing electability arguments
Mills, who was recruited by Senate Minority Leader Chuck Schumer, casts herself as the safer choice to defeat Collins after winning statewide office twice. Platner, who entered the race earlier, quickly secured Sen. Bernie Sanders’s endorsement and has drawn energized crowds by arguing that national Democrats have abandoned working-class Mainers and by rejecting what he calls Washington’s “same old” playbook.
Platner’s campaign was set back last fall when media reports resurfaced old offensive social media posts and a tattoo with imagery critics said echoed Nazi symbolism; he has acknowledged both. Still, recent polls from the University of New Hampshire Survey Center and Pan Atlantic SMS have shown him leading among likely Democratic primary voters.
Mills has seized on Platner’s past posts in ads aimed at female voters, highlighting a 2013 Reddit entry that contained language many found objectionable. Platner held a media event with women who support him and issued an apology, saying the posts reflected anger and disorientation after combat tours in Iraq and Afghanistan and did not represent who he is today. His campaign also ran a television response addressing Mills’s attacks.
Who is spending what
Platner has outspent Mills on advertising and reported stronger fund-raising totals. AdImpact tracked roughly $4.2 million in ad spending by Platner compared with about $1.16 million by Mills during the same period. Federal Election Commission filings show Platner’s campaign raised nearly three times what Mills had through last year.
Much of the outside Democratic-aligned spending has focused on attacking Collins rather than elevating one primary contender. Collins herself has scarcely opened her own wallet for the contest, reporting about $240,000 in spending to date. By contrast, outside Republican groups — most prominently One Nation, which operates as an issue-advocacy organization that does not disclose donors — have invested heavily on Collins’s behalf, spending just over $10 million on ads, digital outreach, texts and mailers emphasizing her record securing federal funding.
Strategic trade-offs and risks
Political scientists say the early outlays make strategic sense: Platner needs to build name recognition across the state, while Mills is trying to define him before the primary and position herself as the nominee best suited to beat Collins. Ron Schmidt, a political science professor at the University of Southern Maine, warned that Mills’s attacks targeting Platner’s past could alienate his supporters and make it harder for Democrats to unite in the general election.
Mills frames her campaign around electability and a willingness to confront former President Donald Trump; she has argued voters should hear Platner’s own words. Platner, calling the criticism an establishment effort to undermine his candidacy, says he represents bold change and thanked supporters for backing his insurgent bid.
With Collins largely allowing outside groups to defend her, the Democratic primary looks likely to remain costly and contentious. How the party reconciles the intra-party fight after the primary will shape its chances of consolidating behind a single challenger in November.