Soon after news broke Monday that a woman who had previously dated Maine Democratic Senate candidate Graham Platner accused him of rape — an allegation he has denied — his campaign reached out to former Sen. Barbara Boxer.

The retired California Democrat had drafted an op-ed backing Platner and criticizing the record of her former Republican colleague, Maine Sen. Susan Collins. As droves of his allies began rescinding their endorsements and calling on him to drop out Monday, Platner’s campaign wanted to know if the article should still run, Boxer said.

She told them no.

“I still feel the way I do about Susan Collins, but I can’t support Graham Platner based on what’s come out,” Boxer told CNN on Wednesday. “I fought my whole life protecting women and can’t do it.”

Until this week, Platner had been able to withstand an onslaught of controversies over his old social media posts, a tattoo that resembles a Nazi symbol, his infidelity and accusations of unsettling behavior with former romantic partners. His stunning political rise, supporters said, showed that people can change and that his movement was stronger than the establishment forces that viewed him as a weak general election candidate.