WASHINGTON ― The Senate Intelligence Committee is exploring ways to compel President Donald Trump to hand over any potential audio recordings of now-former FBI Director James Comey, an aide with the committee told HuffPost.

But officials are grappling with two potential hurdles: They don’t actually know if the tapes exist, and likely will face fierce pushback from the White House if they request them.

“There’s no simple mechanism, but you can be sure we’ll take a look at it,” the committee aide said.

On Friday morning, Trump suggested in a tweet that there were “tapes” of his conversations with Comey, adding that he would release them if Comey leaked information about his firing to the press. The White House refused to deny that such recordings actually exist, with press secretary Sean Spicer saying only that the president had nothing to add beyond his tweet.

James Comey better hope that there are no "tapes" of our conversations before he starts leaking to the press! — Donald J. Trump (@realDonaldTrump) May 12, 2017

If there are recordings of conversations between Trump and Comey, they could resolve a number of lingering questions. Trump claims he received assurances from Comey that he is not under FBI investigation, but it would be highly unusual for Comey, who was leading the bureau’s investigation into possible collusion between Trump campaign associates and Moscow, to discuss the probe with Trump. Allies of the ousted FBI director dispute Trump’s version of events, telling The New York Times that Trump demanded “loyalty” from Comey.

The Senate Intelligence Committee ― which is also probing connections between the Trump team and Russian officials ― does not necessarily need to have proof that the tapes exist in order to subpoena them, Bradley Moss, a national security lawyer, told HuffPost. Senate investigators could ask for “any recording devices or backup copies that were referenced in the post made by President Trump on the morning of May 12, with respect to recordings with President Trump and Director Comey,” said Moss.

But the chairman of the committee has final say over whether any subpoenas will be issued, and it was unclear as of Friday afternoon if Sen. Richard Burr (R-N.C.) is on board.

On the House side, meanwhile, a spokesperson for the chair of the Intelligence Committee, Mike Conaway (R-Texas), declined to comment. Rep. Adam Schiff (D-Calif.), the ranking member of the House Intelligence Committee, called on Trump to “immediately provide any such recordings to Congress or admit” that his statement was not true. But Schiff notably did not mention using subpoena power to compel Trump to turn over recordings.

Even though investigators have the authority to subpoena the tapes, there is no guarantee the White House will agree to give them up ― or even say definitively whether they exist. Matthew Miller, a former spokesman for the Department of Justice, questioned whether Congress could successfully subpoena all of the tapes, citing a potential “separation of powers issue.”

“It’s why Cabinet officials testify, turn over the emails to Congress, but White House staffers never do,” Miller emailed.

The president could invoke executive privilege and move to quash the request, which Moss predicted would spark a protracted legal battle.

“They could very much relitigate the legal battle that Nixon had and ultimately lost over [his] tapes,” he said.

If Trump is recording conversations, he would be legally required to preserve copies, former White House lawyer Daniel Jacobson tweeted. Deleting the recordings could be a criminal offense, he wrote.

If Trump is actually taping convos, the Pres Records Act requires they be archived, and would violate criminal law (18USC641) to delete them — Daniel Jacobson (@Dan_F_Jacobson) May 12, 2017

Another issue that investigators are grappling with is whether the act of surreptitiously recording a conversation is legal. Aides said the topic was debated among staff on Friday morning, but it appeared likely enough that Trump was in the clear.

“The biggest question is if they exist at all,” said a Democratic aide on the House Intelligence Committee.