Calls for Graham Platner, the Democratic candidate for US Senate in Maine, to withdraw his candidacy intensified Monday after a woman accused him of sexual assault in an exclusive report by Politico.

While Platner denied the claims, many top Democratic figures quickly called on the beleaguered nominee to step down.

In a joint statement, Senate Democratic leader Chuck Schumer and Democratic Senatorial Campaign Committee chair Kirsten Gillibrand said Platner should “immediately withdraw”.

“The allegations reported today are incredibly disturbing – violence, abuse and sexual assault are absolutely unacceptable,” they said. “The DSCC will not invest in the Maine Senate race if Platner remains on the ballot.”

Maine’s Democratic party leadership said Platner should withdraw from the race, while Ro Khanna, the California representative who has been one of Platner’s most vocal supporters, also said he should drop out. “I’ve been very clear that sexual assault or violence against women is a red line,” he wrote on X. “These allegations are very serious and credible. Graham Platner should drop out from the race. I am withdrawing my endorsement.”

Ruben Gallego, a Democratic senator from Arizona, also said on X: “The allegations against Graham Platner are troubling and deeply serious. I am rescinding my endorsement.”

Jenny Racicot, 41, dated Platner, an oyster farmer and former marine veteran, and she alleges in the Politico report he forced her to have sex despite repeated objections.

Platner denied the claims in a statement to Politico.

“These allegations are troubling, serious, and false. Any accusation of non-consensual behavior is categorically untrue,” he said.

Racicot told the outlet she had an on-and-off relationship with Platner for more than two years. She alleges that in late 2021, an intoxicated Platner entered her home uninvited and forced himself on her. Racicot said she terminated contact after the encounter.

The report cited accounts from a man Racicot later confided in, as well as therapist emails and messages where she warned an acquaintance about Platner years before his Senate run.

Platner, who secured the Democratic nomination and faces the Republican senator Susan Collins in the general election, has faced a series of scandals.

Platner has cast himself as a populist everyman with an anti-oligarchy message. Before his run for public office, he made controversial comments on social media and got a Nazi-linked tattoo, which has since been covered up. Platner has said he did not initially understand the meaning of the tattoo.

In a video message, Platner again said the accusations were false, but that he was mindful of the political reality the accusation will carry.

“We are taking the time to reflect on the best path forward for the state that I love, the people that I love, the movement I belong to and the goal of defeating Susan Collins,” Platner said.

He thanked the voters who helped propel him to the nomination as a political newcomer.

“You never turned your back on me, and I will not turn my back on you now,” he said. “Every one of you deserves to see that vision come to fruition, and see Susan Collins defeated, and we will use every tool at our disposal to do so. As Maine goes, so goes the nation.”

Collins herself weighed in on social media: “These allegations are appalling. Nevertheless, it is not up to me to choose the Democratic nominee for Senate.”

Racicot was one of several women who spoke to the New York Times for a previous story in June about Platner’s “unsettling” behavior with women he dated.

She told Politico she hesitated to make her claim public because she had a “huge moral conflict” between supporting Platner’s politics and not supporting him as a person. She also said she did not share the sexual assault claims with the New York Times for their story because she did not want to be known as a rape victim.

Racicot told Politico she had previously had consensual relations with Platner, until a night in 2021 when he allegedly let himself into her unlocked house and forced himself on her. She said she repeatedly told him to stop and that she believed he was “almost blackout drunk”.

According to Politico, Racicot accused Platner of having sex with her against her will and ejaculating inside her after she told him not to. There was no police report filed at the time.

Platner’s campaign said the senatorial candidate “vigorously denies” the claims.

“These allegations are very serious and Graham vigorously denies them,” the statement said. “They are also coached and coordinated by out of state establishment operatives. For a year, opponents of this campaign have thrown everything they can at Graham – calling him a Nazi, a war criminal, and a communist. None of it has been true and this is no different.

“It is not a coincidence that this story comes a week before the ballot deadline, just as the previous false allegations came a week before the primary. Graham began this campaign to fight for a Maine where everyone is treated with dignity and where Mainers are put first, and no amount of desperate smears will stop this movement from seeing that vision through.”

Should Democrats decide to replace Platner as the party’s nominee in the Maine Senate race, Platner would have to drop out by 5pm ET on 13 July, according to state law. The Democratic party will then have a two-week window – until 27 July – to select a replacement candidate.