At least three House Republicans — Reps. Jason Chaffetz of Utah, Darrell Issa of California and Tom Cole of Oklahoma — have said they want Sessions to withdraw from the inquiry. And GOP Sen. Rob Portman of Ohio said that while Sessions was a former colleague and a friend, "I think it would be best for him and for the country to recuse himself."

The attorney general "is going to need to recuse himself at this point," Chaffetz, chairman of the House Oversight and Government Reform Committee, told MSNBC.

House Majority Leader Kevin McCarthy, R-Calif, said he thought Sessions "needs to clarify what these meetings were." He said it isn't unusual for members of Congress to meet with ambassadors, but he added that if a question arose about the integrity of a federal investigation, "I think it'd be easier" for an attorney general to step away.

House Speaker Paul Ryan said Sessions should only recuse himself if he is a subject of the probe.

Sessions, an early supporter of President Donald Trump's candidacy and a policy adviser during the campaign, did not disclose those discussions at his Senate confirmation hearing in January when asked what he would do if "anyone affiliated" with the campaign had been in contact with officials of the Russian government.