Embattled national security adviser Michael Flynn's fate as one of President Donald Trump's senior aides is uncertain following reports that he discussed U.S. sanctions with a Russian envoy before Trump's inauguration.

A top White House official sidestepped repeated chances Sunday to publicly defend him. The president, who spent the weekend at his private club in Florida, has yet to comment on Flynn's status. Nor has Vice President Mike Pence, who previously denied that Flynn had discussed sanctions with Sergey Kislyak, the Russian ambassador to the U.S.

Flynn was a loyal Trump supporter during the campaign, but he is viewed skeptically by some in the administration.