Senate Majority Leader Mitch McConnell urged Roy Moore, his party’s candidate for Senate in Alabama, to quit the race, saying the women who have accused the former state chief justice of sexual advances on them when they were teens have told a compelling story.

“I believe the women,” Mr. McConnell told reporters, according to the Associated Press.

He said the GOP is considering whether to mount a write-in campaign for someone else.

Mr. Moore’s campaign has been reeling since a report in The Washington Post last week in which several woman said Mr. Moore decades ago, as a lawyer in his 30s, pursued relationships with them when they were anywhere from 14 to 18 years old.

Mr. Moore has denied the allegations and says he’s the victim of a smear campaign, but Mr. McConnell’s comments suggest that isn’t assuaging GOP leaders in Washington.

Mr. McConnell had been an opponent of Mr. Moore’s throughout the race, backing another candidate in the GOP primary earlier this year. And last week Mr. McConnell said that if the allegations were true, Mr. Moore should step aside.

But his comments Monday went further, saying it was time for Mr. Moore to go.

Mr. Moore, who’s said he’s not going anywhere, said on Twitter Monday that it’s Mr. McConnell who should give up his post.

“He has failed conservatives and must be replaced,” Mr. Moore wrote, adding “#DrainTheSwamp.”

Even a Moore withdrawal would not solve the GOP’s problems, with the election looming in a month and ballots having been printed weeks ago. State law also seems stacked against the GOP replacing the name on the ballot, leaving a write-in campaign the only option if Republicans want to try to keep the seat without Mr. Moore.

And some conservative groups and Alabama voters are rallying to Mr. Moore, turning his fight with GOP leaders into the latest intraparty skirmish.

“These accusations that Moore had an improper relationship with a 14-year-old girl in 1979 are obviously manufactured charges from the Washington Post,” said William Gheen, President of Americans for Legal Immigration Political Action Committee.