National Security Adviser Michael Flynn sits in the front row before the start of the joint press conference by President Trump and Japanese Prime Minister Shinzo Abe on Friday at the White House. (Carolyn Kaster/AP)

National security adviser Michael Flynn spoke privately with Vice President Pence on Friday in an apparent attempt to contain the fallout from the disclosure that Flynn had discussed U.S. sanctions on Russia with that country’s ambassador and then allowed Pence and other White House officials to publicly deny that he had done so, an administration official said.

The conversations took place as senior Democrats in Congress called for existing investigations of Russia’s interference in the 2016 election to expand in scope to scrutinize Flynn’s contacts with Russian Ambassador Sergey Kislyak weeks before the Trump administration took office.

Rep. Adam B. Schiff (Calif.), the ranking Democrat on the House Intelligence Committee, said that if the allegations are proved, Flynn should step down.

“If the now national security adviser was undermining U.S. national security interests, he’s unfit to hold that office,” Schiff said in an interview with The Washington Post. “Compounding the issue is whether he then misled the country about the nature of his contacts.”

(Bastien Inzaurralde/The Washington Post)

Current and former U.S. officials said that in his conversation with Kislyak in late December, Flynn urged Moscow to show restraint in its response to punitive sanctions being imposed on Russia by the Obama administration, signaling that the Trump administration would revisit the issue when it took office.

That contact was seen by some U.S. officials as potentially illegal interference in the U.S. relationship with Moscow at a time when U.S. intelligence agencies were concluding that Russia had waged extensive cyber and influence campaigns to upend the 2016 presidential race and help to elect Donald Trump.

President Trump claimed to be unaware of the Flynn controversy as he traveled to Florida on Friday afternoon as part of a weekend trip with Japanese Prime Minister Shinzo Abe. In a brief exchange with reporters during the flight south, Trump was asked about the report in The Post that Flynn had discussed sanctions against Russia despite repeated denials.

“I don’t know about that, I haven’t seen it,” Trump said, according to a transcript of the conversation. “What report is that? I haven’t seen that. I’ll look into that.”

Flynn’s relationship with Pence was placed under particular strain because the vice president — apparently relying on inaccurate accounts from Flynn — publicly declared that Flynn had never discussed sanctions with the Russian diplomat.

A senior administration official said Flynn and Pence spoke in person Friday morning and by phone in the evening. Officials declined to discuss the outcome of the conversations. The two men could be seen engaging in an awkward handshake during the day while taking their seats in the audience for Trump’s news conference with Abe.

The controversy fanned speculation about Flynn’s standing in the White House and whether he would face pressure to resign. The senior administration official disputed that Flynn was in jeopardy.

“He seems fine,” the official said, speaking on the condition of anonymity to discuss sensitive internal matters. “He’s in every meeting he’s supposed to be doing, fulfilling his job as national security adviser. He’s seeing the president constantly.”

Flynn also traveled to Florida with Trump.

Republicans were quiet on the matter Friday, but senior Democrats called for investigations of Flynn’s contacts with Kislyak. Sen. Claire McCaskill (Mo.), ranking Democrat on the Senate Homeland Security Committee, called for FBI Director James B. Comey to testify before the committee on the status of the bureau’s examination of Flynn’s calls.

Schiff said that he intends to request the intelligence reports on Flynn’s conversations with the Russian ambassador. Their contacts were captured as part of routine U.S. intelligence surveillance of Russian officials in the United States.

“This is one discrete set of allegations that ought to be simple to prove or disprove,” Schiff said. “If these allegations are true, it ought to compel him to step down.”

Sens. Richard Blumenthal (D-Conn.) and Jeanne Shaheen (D-N.H.), both members of the Senate Armed Services Committee, wrote Secretary of Defense Jim Mattis and CIA Director Mike Pompeo requesting a review of Flynn’s security clearance.

Ashley Parker contributed to this report.