By Jonathan Martin and Alex Burns

New York Times News Service

WASHINGTON — Sen. Mitch McConnell of Kentucky, the Senate majority leader, said on Thursday that if Roy Moore made sexual overtures to four women when they were teenagers, as they allege, the Republican Party nominee for a Senate seat in Alabama should step aside ahead of a Dec. 12 special election.

“If these allegations are true, he must step aside,” McConnell said after The Washington Post posted a story online in which the women said in on-the-record interviews that Moore had pursued them in the 1970s and 1980s when he was an attorney in his 30s.

Moore was defiant, denying the charges and attacking the media.

“These allegations are completely false and are a desperate political attack by the National Democrat Party and The Washington Post on this campaign,” he said.

Brett Doster, an adviser to Moore, said the candidate would “absolutely not” drop out of the race, calling the charges “a fabricated November surprise.” Doster said the campaign had not heard from McConnell or any Senate leaders.

But Moore’s candidacy was in grave danger. Senate Republicans moved en masse to distance themselves from their nominee almost as soon as the news story was posted.

“If these allegations are true, his candidacy is not sustainable,” said Sen. John Cornyn of Texas, the second-ranking Republican. Cornyn said he wanted to know more before withdrawing his endorsement of Moore.

Those statements were repeated by numerous Republican senators.

Republicans, reeling from the election losses they suffered Tuesday, have only a two-seat majority in the Senate and are facing a handful of difficult elections next year.

Moore’s candidacy had worried party leaders who had embraced the controversial former state Supreme Court justice despite his long record of incendiary comments about gays, Muslims and African-Americans, to protect the Senate seat once held by Attorney General Jeff Sessions.

But Alabama election law appears to indicate, with little ambiguity, that the deadline has passed for candidates to be replaced on the ballot. The state election code says a candidate who wishes to withdraw from a race must do so 76 days before Election Day. The Alabama vote is in little more than a month.