Top Trump administration officials cautioned Sunday that Roy S. Moore, the Republican Senate nominee in Alabama, should be allowed to defend himself against allegations that he pursued sexual and romantic relationships with teenage girls, even as Senate Republicans appeared to have largely abandoned his candidacy.

And Marc Short, the White House’s legislative director, said he expected that President Trump would give the matter more attention when he returns from an extended trip through Asia later this week.

“I think the president’s obviously on a very important trip, and when he returns I think we’ll have that conversation,” Mr. Short said on NBC’s “Meet the Press.”

The accusations against Mr. Moore have consumed political circles from Alabama to Washington since Thursday, when The Washington Post published the accounts of four women accusing Mr. Moore of misconduct. Senate Republicans have made their stance relatively clear, pulling out of a joint fund-raising agreement with Mr. Moore’s campaign and rescinding endorsements in the days since the allegations came to light.