Republican Sen. John Barrasso told CNBC on Monday that sexual misconduct allegations against Roy Moore are "disturbing," and Moore should drop out of Alabama's race if true.

Moore, the 70-year-old GOP nominee for a special Senate race in Alabama, was accused by a woman of initiating a sexual encounter when she was 14 years old and he was 32. Three other women said he pursued them when they were 16 to 18. Their accounts were published last week by The Washington Post.

"These charges seem very credible, they're very disturbing," said Barrasso, the fourth-ranking member in the Senate Republican leadership. "If true, he should move aside."

"There's a month between now and the election," the Wyoming senator told "Squawk Box." "Ultimately, the people of Alabama are going to have to make that decision."

When asked whether Republicans would need Moore's vote to pass tax reform, Barrasso only said, "You can get into the issues of when one senator leaves and another comes in. We need 50 votes and the vice president to break a tie."

Moore has denied any wrongdoing, calling allegations "completely false and misleading." He has threatened to sue the Post.

Other Republicans, including President Donald Trump and Senate Majority Leader Mitch McConnell, have called on Moore to withdraw from the race if the claims are found true.

GOP Sen. Pat Toomey urged Moore to drop out now, saying on NBC's "Meet the Press" on Sunday that Moore's explanations had been inadequate and Republicans should consider Sen. Luther Strange as a write-in candidate to run against Moore. Strange lost the Republican primary to Moore in September. Moore was backed by former top Trump aide Steve Bannon. Strange was backed by Trump and McConnell.

—Reuters and AP contributed to this report.