Most Republicans pursued similar arguments, deflecting questions about the need for further investigations into the administration’s ties to Russia. But a handful expressed concern about the pace of progress.

“It is frustrating to understand how we’re going to get a full, in-depth look at all the things that have happened,” said Senator Bob Corker, Republican of Tennessee, chairman of the Foreign Relations Committee. “I think this episode does heighten the intensity around wanting to make sure that it’s fulsome and that we understand all aspects of what’s occurred.”

Senator Lindsey Graham, Republican of South Carolina, identified a possible silver lining.

“I just think it makes it almost impossible for them to lift sanctions now,” said Mr. Graham, who introduced bipartisan legislation last week that would require congressional approval for Mr. Trump to lift sanctions against Russia. “That’s sort of the good news.”

Mr. Graham suggested, gently, that Republicans should take care to avoid any appearance of hypocrisy.

“I think it’s important for us to be informed about the phone call. Did he do it by himself? Did he kind of go rogue or did somebody suggest to him to call the Russians?” he said. “I know we would be upset as Republicans if the Obama administration had done this.”