A top House Democrat suggested this week that Fox News host Sean Hannity should be subpoenaed to testify before Congress to determine what he knows about hush-money payments Michael Cohen allegedly made on President Donald Trump's behalf.

What are the details?

During testimony before the House Oversight Committee Wednesday, Cohen told Congress that he made several hush-money payments at Trump's request.

But Hannity contradicted Cohen's testimony during an interview with Trump on his Fox News show Thursday. In fact, Hannity said Cohen told him personally that Trump did not direct him to cut the payments.

"I can tell you personally, [Cohen] said to me, at least a dozen times, that he made the decision on the payments and he didn't tell you," Hannity told Trump.

Where does a subpoena come in?

According to Rep. David Cicilline (D-R.I.), Hannity "volunteer[ed] himself as a witness" and should therefore inform Congress under oath what he knows about the situation.

"Sean Hannity volunteered first-hand knowledge about Michael Cohen's actions last night. If he was lying, it wouldn't be the first time. This is the same guy who claimed inside knowledge that Russia didn't hack the DNC until a federal judge ordered him to stop. Regardless, if he feels he has information that's relevant to this investigation, he should share it under oath before Congress," Cicilline's spokesman later told CNN.