Flynn apologized to Pence for misleading him about Russia call: official

Flynn and the Russian ambassador discussed sanctions ahead of the inauguration.

— -- Embattled National Security Adviser Michael Flynn called Vice President Mike Pence Friday to apologize for misleading him about a conversation with the Russian ambassador to the United States, according to a senior White House official.

Further details about the call between Flynn and Pence were not immediately available.

Flynn has denied that he spoke about the sanctions during his dialogue with the ambassador, but a senior administration official appeared to back off that denial late last week, saying Flynn doesn't recall discussing the sanctions but "isn't completely certain."

In January, Pence -- relying on information gleaned directly from Flynn, according to a senior administration official -- said during an interview with CBS: "They did not discuss anything having to do with the United States’ decision to expel diplomats or impose censure against Russia."

Rep. Adam Schiff, D-California, the top member of the party on the House Intelligence Committee, released a statement Friday saying that the allegations raise “serious questions of legality and fitness for office,” and that if they are proven true, that Flynn “should no longer serve in this administration or any other.”

“We have a national security adviser who cannot be trusted not to put Putin before America,” said Pelosi.

U.S. authorities continue to investigate communications between Flynn and Russian officials, but have yet to find any clear evidence of wrongdoing.

ABC News' Jonathan Karl contributed to this report.