WASHINGTON - US lawmakers on Sunday called on President Donald Trump to turn over any tapes of conversations with fired FBI chief James Comey, potentially setting up a showdown with the White House as Democrats considered a boycott of the vote on Comey's replacement.

In a highly unusual move, Trump last week appeared to suggest that he might have tapes of conversations with Comey and warned the former director of the Federal Bureau of Investigation against talking to the media. Trump and a White House spokesman declined to confirm or deny whether such tapes exist.

Republican Senator Lindsey Graham of South Carolina said the White House must "clear the air" about whether there are any taped conversations.