This post has been updated with comments from the White House about handing over the tapes.

Press secretary Sean Spicer May 15 refused to answer questions about recordings of White House phone calls. (Reuters)

Top Democrats and Republicans in Congress may say they want to get their hands on any tapes President Trump may have made of his conversations with FBI Director James B. Comey, which could lend clues as to why Trump fired him.

And if the president won't hand them over, Congress could force him to. But almost no one in Congress seems willing to take that step.

First, how Congress could get the tapes: House Democrats have already sent a letter to the White House asking for them. But on Monday, White House Press Secretary Sean Spicer wouldn't even acknowledge the tapes exist much less agree to give them to Congress. Spicer said the president "has nothing further" on the tapes beyond his extraordinary tweet Friday suggesting he or someone else recorded his conversations with Comey.

Congress could require Trump to prove they exist by issuing a subpoena to hand them over. A subpoena would essentially put the president afoul of the law if he doesn't give Congress the recordings.

But issuing a subpoena is a serious thing, and it requires both Democrats and Republicans to agree to it. The Senate Intelligence Committee recently issued a subpoena to force Trump's former national security adviser, Michael Flynn, to hand over documents related to the committee's Russia investigation. The subpoena happened after Trump had dropped Flynn like a hotcake, and there's no indication Republicans are willing to put their president on the spot like they have Flynn. In fact, very few Democrats are even talking about a subpoena.

Sen. Lindsey O. Graham (R-S.C.), one of the most vocal Republicans in the Senate to be asking for the tapes, seems interested in forcing Trump to hand them over. “You can't be cute about tapes. If there are any tapes of this conversation, they need to be turned over,” Graham told NBC television’s “Meet the Press,” on Sunday.

After President Trump suggested that he taped his conversations with former FBI director James B. Comey, lawmakers of both political parties on May 14 said Trump ought to release any recordings that may exist. (Bastien Inzaurralde/The Washington Post)

But Graham didn't say whether he'd support a subpoena to get the tapes. His office declined to elaborate except to point to the fact that subpoenas are traditionally used for criminal investigations and Trump's firing of his FBI director is not one.

Sen. Mike Lee (R-Utah) appears to be the only Senate Republican open to a subpoena. He told "Fox News Sunday": "I think is probably inevitable at this point. If, in fact, there are such recordings, I think those recordings will be subpoenaed and I think they will probably have to turn them over."

During the Sunday show circuit, Sen. Mark Warner (D-Va.), the top Democrat on the Senate intelligence committee, was one of the few Senate Democrats talking subpoena.

A subpoena isn't Congress's only tool to force Trump's hand: It could also vote to hold the president in contempt of Congress or even use a long-dormant power to hold him or people involved in the taping in jail until he complies.

All of this would, obviously, be a significant escalation between Congress and the White House. And since no one in Washington is even sure if Trump actually recorded his conversations with Comey, you can see why Republicans seem averse to entertaining the idea of subpoenaing the president: It could be a huge battle over nothing.

An important caveat: Democrats don't need ALL Republicans in Congress to help them force Trump to hand over tapes/call the president's bluff. They only need a handful of Republicans. Let's look at the Senate, where most of the conversations about the tapes seems to be centered, for how this could work:

1) The chair of a committee that oversees the FBI agrees to issue a subpoena.

The two committees that have jurisdiction over the FBI are the Senate Intelligence and Senate Judiciary committees.

BUT: Since Republicans control Congress, both are controlled by Republicans — Sens. Richard Burr (N.C.) and Charles E. Grassley (Iowa), respectively. And neither has expressed any interest in subpoenaing the president; neither has even indicated they want to see the tapes.

2) A majority of committee members vote to issue a subpoena. In the Senate Intelligence Committee, which is investigating Trump-Russia ties, that would mean all Democrats and at least one Republican would have to vote to issue a subpoena. In the Senate Judiciary Committee, which Graham and Lee sit on, Democrats would need at least two Republicans to join them.

BUT: Here, too, Republicans have the upper hand. On the Senate Judiciary Committee, Democrats' most sympathetic ear would probably be Graham or Lee. For now, Graham doesn't seem supportive of the idea.

The bottom line: Anyone in Congress who wants to see Trump's “tapes” will have to rely on the power of persuasion to get Trump to hand them over, or hope that Republicans suddenly see a political upside to putting their president on the spot and/or calling his bluff.