BAR HARBOR, Maine — Outside the Criterion Theatre, Graham Platner’s Senate campaign was in shambles, chastised by some Democrats and abandoned by others. Inside the building, 500 Mainers greeted him as a flawed, relatable hero.

The crowd even chanted his wife Amy’s name when he acknowledged their nearly three-year-old marriage had its stumbles, exposed last week in newspapers of record that documented his sexual messages to other women.

“When hurtful things I said on the internet a decade ago came out into the public, as I shared my personal journey through PTSD and darkness of recovery and accountability and growth — Maine had my back,” Platner said.

He then alluded to the second hit of negative coverage, a New York Times report on three former girlfriends who recalled occasionally volatile and intimidating behavior that he has denied: “And when politically motivated, serious, and false accusations are made against me: Maine, you have my back.”

Pulled from obscurity last year by labor unions and progressive strategists, Platner has become the kind of candidate both parties dread: one whose words and messy personal life keep throwing them off-message. What started as a drive to find working-class candidates outside the party’s usual bench is now a potential problem for Democrats everywhere, not least because Platner has no intention of heeding pressure to step aside.

Maine Democrats will decide on Tuesday whether to nominate him to face Sen. Susan Collins, a Republican seeking her sixth term. Gov. Janet Mills, who suspended her bid when Platner built an overwhelming poll lead, is reminding voters that she’s still on the ballot. David Costello, a Democratic activist, warned that Platner is “starting to bleed support.”

“All of us are fairly nervous about his chances, and what information Republicans might be holding back about him until the primary’s over,” added Costello, who said more people had been showing up to his meet-and-greets.

The Platner team is projecting confidence that it understands Maine voters much better than the DC professionals. Morris Katz, Platner’s lead strategist, told Semafor that the campaign’s message was always built on “redemption,” and that the candidate spoke to the kind of man who didn’t vote for Democrats anymore.

“He was ashamed of some of the things he said and did. Unlike others, he took accountability for it,” said Rep. Ro Khanna, D-Calif., in Bar Harbor. Khanna added that Platner had made mistakes, but they weren’t all his fault; he described the candidate as an avatar for “thousands of young men” whose lives were broken by “dumb wars.”

Encapsulating the fine line the Platner campaign has to walk, Khanna also said Platner should apologize to the ex-girlfriends who described his mistreatment of them.