Several senators called Sunday for President Donald Trump to hand over any tapes he might have of conversations between himself and former FBI director James Comey, who was abruptly fired last week.

Trump appeared to suggest on Twitter Friday that there could be recordings. His tweet warned Comey that he had “better hope that there are no ‘tapes’ of our conversations before he starts leaking to the press!” White House Press secretary Sean Spicer declined to specify whether or not such tapes exist.

“If there are any tapes of this conversation, they need to be turned over,” Sen. Lindsey Graham of South Carolina said on NBC’s Meet the Press on Sunday. Graham also suggested that the President should stop commenting on social media about the ongoing investigation into alleged links between Trump’s campaign staff and the Russian government, which was being led by Comey.

The Trump administration said Comey was fired because of how he handled the probe into Hillary Clinton’s use of a private email server, though some lawmakers and analysts have suggested the decision may have been related to Comey’s separate investigation into Russian interference in the 2016 election.

Read More: James Clapper: U.S. Government Is ‘Under Assault’ After James Comey Firing

Sen. Mike Lee of Utah said on Fox News Sunday that recording conversations in the White House would be “not necessarily the best idea,” and that it would be “inevitable” that such tapes would be subpoenaed if they do, in fact, exist.

Speaking on CNN’s State of the Union, Senate minority leader Chuck Schumer said that if tapes exist, destroying them would be illegal and they must be immediately turned over to Congress and investigators. “If there are no tapes, he should apologize to both Jim Comey and the American people,” Schumer said.

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