Trump comments echoed those of at least eight other Republicans, some of whom had been withholding full backing for the controversial former state Supreme Court judge.

Vice-President Mike Pence found the accusations disturbing and if proven true “would disqualify anyone from serving in office,” his spokeswoman Alyssa Farah said.

“If these allegations are true, Roy Moore should step aside for all the obvious reasons,” Senate Majority Leader Mitch McConnell, who backed Moore’s opponent in the Republican primary, said Thursday. He said the allegations are “very disturbing”.

The allegations, reported by The Washington Post Thursday, recast an already tumultuous Senate campaign, in which Moore defeated a primary opponent supported by McConnell and the party establishment and likely was headed toward a victory over the Democratic candidate in solidly Republican Alabama.

The Post reported that four women said Moore, now 70, asked them on dates when they were ages 14 to 18 and he was in his early 30s.

One of them told the newspaper that he initiated sexual contact with her after taking her to his home. The three others said their encounters didn’t go that far.

“It is no surprise, with just over four weeks remaining, in a race for the US Senate with national implications, that the Democratic Party and the country’s most liberal newspaper would come up with a fabrication of this kind,” Moore’s campaign chairman, Bill Armistead, said in a statement.

“This garbage is the very definition of fake news and intentional defamation.”

Moore won the Alabama Republican Party nomination to fill Attorney General Jeff Sessions’s former Senate seat, beating incumbent Senator Luther Strange in a September 26 run-off vote.

He will face Democrat Doug Jones, a former US lawyer, in the December 12 election.

Moore currently leads Jones by 6 percentage points, according to an average of statewide polls compiled by Real Clear Politics.

Before Thursday’s report, Jones was seen as an underdog in a state that gave Donald Trump 62.9 per cent of the vote and hasn’t sent a Democrat to the Senate since the 1990s.

In a brief statement, Jones’s campaign said only that “Roy Moore needs to answer these serious charges.”

“It’ll be interesting to see if the Jones campaign can draw a strong contrast,” said David Mowery, a Montgomery, Alabama-based political consultant who has worked with Democrats and Republicans. Mowery said that Jones should aggressively court female voters and hope that Republicans start to rescind their endorsements. But he said he doubted this would end Moore’s campaign.

“Obviously it’s a big deal, but I don’t know right now that it’s a death knell,” he said.

Alabama law doesn’t allow the removal of a name from a ballot so close to the election. But if Moore were to withdraw – and there was no immediate indication he would – state law says votes cast for him wouldn’t be certified.

John Cornyn of Texas, the No. 2 Senate Republican, who had endorsed Moore, called the report “deeply troubling and disturbing”.

Moore was also endorsed by senators Mike Lee of Utah, Steve Daines of Montana, Ted Cruz of Texas and Rand Paul of Kentucky, who held a fundraiser for the Moore campaign in Washington last week. A spokesman for Lee echoed McConnell, calling on Moore to quit if the allegations are true.

Senator Richard Shelby, an Alabama Republican who endorsed Moore’s primary opponent Luther

Senator John McCain of Arizona delivered an unequivocal denunciation of Moore, saying he should “immediately step aside and allow the people of Alabama to elect a candidate they can be proud of.”

Coincidentally, the Senate on Thursday unanimously adopted a resolution requiring anti-harassment training for senators and employees of the chamber.

Moore is known outside Alabama mostly for being removed twice as chief justice of the state Supreme Court – in 2003 for refusing to take down a Ten Commandments monument from the Alabama judicial building, and in 2016 for telling state judges not to issue marriage licenses to same-sex couples after the US Supreme Court legalised gay marriage.

He also has a history of controversial statements, including writing that Muslims like Representative Keith Ellison, a Minnesota Democrat, shouldn’t serve in Congress and that transgender people don’t have rights.

The allegations against Moore come at a time when prominent men in the entertainment industry, business and politics have been accused of multiple acts of sexual misconduct. The wave of accusations was led by reports from The New York Times and The New Yorker detailing accusations of sexual harassment and assault against film executive Harvey Weinstein.

The 14-year-old, identified by The Post as Leigh Corfman, said Moore initially approached her outside a courtroom in Etowah County, Alabama, when he was an assistant district lawyer. He began a conversation and offered to watch the girl while her mother went into the courtroom for a child custody hearing, The Post said.

Corfman told The Post that Moore spent time alone with her. He drove her to his house and kissed her, she told the newspaper. On a second visit, he took off his outer clothes, along with her shirt and pants, she told The Post. Moore touched her through her bra and underpants and “guided her hand to touch him over his underwear,” according to The Post.