Graham Platner, the presumptive Democratic nominee for Senate in Maine, moved to quell mounting Democratic anxieties about his candidacy on Friday, telling supporters in a defiant speech that his past behavior was being “weaponized” by his political opponents.
A day after The New York Times reported that three women — a conservative and two Democrats — who had been romantically involved with Mr. Platner described volatile and “toxic” relationships, Mr. Platner addressed a crowd at a theater in Bar Harbor, expressing confidence that Maine voters would stick by him.
“When politically motivated, serious and false accusations are made against me, Maine, you have my back,” Mr. Platner said. “The state of Maine raised me, and the state of Maine saved me, and to all of you out there, Maine, I will always have your back.”
Mr. Platner’s appearance came at a tense moment in one of the year’s premier Senate races. With just days left before Maine’s primary on Tuesday, revelations about Mr. Platner’s personal history have caused escalating discomfort within his party, while drawing intensifying attacks from Republicans.
The rally also took place less than a week after The Times and The Wall Street Journal reported that Mr. Platner’s wife, Amy Gertner, had sought to warn his campaign last year that her husband had been exchanging sexual messages with multiple other women.
Onstage, Mr. Platner referred to Ms. Gertner by name, drawing chants of “Amy!” It was one of the strongest responses from a supportive but relatively sedate crowd that included attendees who said they were anxious about Mr. Platner’s candidacy and still getting to know the candidate.
Mr. Platner said from the stage that he had gone through a period of “darkness” after his military service.
“Now, as every single piece of that past and journey gets dug up, litigated and weaponized, you have my back,” he said.
Outside the theater, Democratic anxieties were growing about Mr. Platner’s chances in a race seen as key to the party’s chances of reclaiming the Senate.
Senator Maggie Hassan of New Hampshire told Punchbowl News that the allegations were “serious and deserve scrutiny.” Representative Madeleine Dean of Pennsylvania told CNN that Mr. Platner had “disqualified himself.” Still other Democrats dodged questions about Mr. Platner or tried to downplay their concerns.
The packed rally, held a few blocks from the Atlantic coast at the nearly century-old Criterion Theater in Bar Harbor, was organized before the Times report, in part by Representative Ro Khanna, a progressive California Democrat who has been a vocal supporter of Mr. Platner’s campaign. In an interview before the rally, he said “we need to respect the women who came forward.” But he added that he had been encouraged by a conversation he had with Mr. Platner in which he said the candidate had acknowledged past “misogyny” and promised that he “grew as a person and as a man.”
While some in the crowd described themselves as enthusiastic supporters of Mr. Platner, others said they were still forming opinions about him — and expressed concern about recent news reports about his past.
The three women who offered critical accounts of dating Mr. Platner told The Times that while spending time with him could be exhilarating, he could also be demeaning to women and, in at least one case, even physically threatening. He drank heavily, they said, and was regularly unfaithful.
Mr. Platner “strongly disputes” any claims of physical intimidation or altercations, his campaign said. The campaign also arranged interviews for The Times with three other women who offered far more positive descriptions of their relationships.
In his remarks, Mr. Platner also attacked Senator Susan Collins, the Republican he is running to unseat, casting her as part of a system of “corrupted politicians.” Earlier in the day, Ms. Collins told local reporters that the allegations in the Times report were “troubling” and that Mr. Platner had “a lot of questions to answer.”
Brody Stofflet, 31, said he came to the event Friday evening to see how Mr. Platner would respond. Mr. Stofflet, who described himself as a swing voter, said he appreciated aspects of Mr. Platner’s message but that some of Mr. Platner’s personal behavior was “nonexcusable.”
“I don’t expect a squeaky-clean politician,” Mr. Stofflet, clad in a baseball cap, said from the back of the theater. But he added that he wanted to see if Mr. Platner had “grown from the mistakes.”
Holly Woodworth, a 57-year-old Democrat sitting near the front, said Mr. Platner was the first politician she had seen “in many elections” whom she felt “inspired by.” She said that the allegations had not shaken her support, and that they hadn’t surprised her given how Mr. Platner had previously described going through a dark period after his military service.
Still, she said the stories about Mr. Platner were making her anxious.
“I care whether the Democrats win the majority,” Ms. Woodworth said, expressing concern that revelations about Mr. Platner’s past would drag down his candidacy, and Democrats’ chances of winning the Senate along with it. “I want a change.”
The rally took place in a House battleground district in northern Maine that is held by Representative Jared Golden, a Democrat who is vacating his seat. Four Democrats are on the ballot in the congressional primary, and Republicans, who are running former Gov. Paul LePage in the district, see a pickup opportunity.
One of the Democratic candidates, Matt Dunlap, the state auditor, attended the rally and said in an interview before the event that he did not know “what to make of” the allegations by Mr. Platner’s past girlfriends. But he added that “people have bad relationships.”
“He’s been very open about it,” Mr. Dunlap said, “and if he continues to do so, I think people will then refocus on the central issues, like health care, child care.”
Jordan Wood, another Democratic House candidate in the district who endorsed Mr. Platner in April and did not attend the rally, said in an interview earlier Friday that the Times report “raises allegations that are very concerning to me — troubling.”
He said he was not withdrawing his endorsement of Mr. Platner. But, he added, “I need to talk to Graham before I say anything beyond that.”
