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LOUISVILLE, Ky. — Senate Majority Leader Mitch McConnell said Monday that Republican Senate candidate Roy Moore of Alabama "should step aside" after a report that he had sexual contact with a 14-year-old girl and an influential GOP senator said he should be expelled from the Senate if he wins.

McConnell, R-Ky., spoke to reporters after visiting a plant in Kentucky and said he believes the women who have come forward with allegations against Moore.

"I think he should step aside," McConnell said.

The Senate Republican leader also said he believes the women who were quoted in a Washington Post story about Moore's past relationships with them as young women.

"I believe the women, yes," McConnell said Monday in response to a question from the media.

The Senate GOP leader had said last week that Moore should step aside only if the allegations were proven true — the position held by President Donald Trump and many Republican lawmakers in Washington, D.C.

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Related: In Alabama, Republican Voters Stand by Roy Moore

Moore has denied the claims and said Sunday he plans to sue the Washington Post. Moore said last week that he didn't know the woman quoted in the Post story alleging he had forced her into a sexual encounter when she was 14 years old and he was 32 in 1979.

"Everybody in this room, every person watching on these cameras, should ask theirselves, 'Isn't it strange that after 40 years of constant investigation people have waited until four weeks prior to the general election to bring their complaints?'" Moore said at an event on Saturday in Vestavia Hills, Alabama.

Moore responded Monday by saying that McConnell's got to go.

The person who should step aside is @SenateMajLdr Mitch McConnell. He has failed conservatives and must be replaced. #DrainTheSwamp — Judge Roy Moore (@MooreSenate) November 13, 2017

National Republican Senatorial Committee Chairman Sen. Cory Gardner, R-Colo., said that if Moore wins, the Senate should vote to expel him.

"I believe the individuals speaking out against Roy Moore spoke with courage and truth, proving he is unfit to serve in the United States Senate and he should not run for office," Gardner said in a statement Monday. "If he refuses to withdraw and wins, the Senate should vote to expel him, because he does not meet the ethical and moral requirements of the United States Senate."

Also Monday, another Republican, Sen. Susan Collins of Maine, said in a tweet that she didn't find Moore's denials convincing and called on him to quit the race, as did a number of other Republicans during the day, including Sens. John McCain, Jeff Flake and Lindsey Graham, among others. Sen. John Cornyn, R-Texas, pulled his endorsement of Moore.

I have now read Mr. Moore’s statement and listened to his radio interview in which he denies the charges. I did not find his denials to be convincing and believe that he should withdraw from the Senate race in Alabama. — Sen. Susan Collins (@SenatorCollins) November 13, 2017

And Sen. Orrin Hatch, R-Utah, said he agreed with McConnell.

I stand with the Majority Leader on this. These are serious and disturbing accusations, and while the decision is now in the hands of the people of Alabama, I believe Luther Strange is an excellent alternative. https://t.co/L7IallXhBc — Orrin Hatch (@OrrinHatch) November 13, 2017

Meanwhile, McConnell said Republicans are exploring a write-in option in Alabama.

"That's an option we're looking at — whether or not there is someone who could mount a write-in campaign successfully," McConnell said.

Asked if Sen. Luther Strange, who lost to Moore in the GOP primary, was being considered for a write-in effort, McConnell said, "We'll see."

Under Alabama law, it is too late for Moore to be replaced before the December 12 election when he is facing Democrat Doug Jones.