Three congressional committees are threatening to subpoena documents for their investigation into President Trump and Rudy Giuliani’s efforts to dig up dirt on Joe Biden in Ukraine.

In a letter to Secretary of State Mike Pompeo on Tuesday, the House Oversight, Intelligence, and Foreign Affairs Committees demanded the Trump administration start turning over the paperwork this week.

Since late last year, Giuliani, in his capacity as Trump’s personal attorney, has been on a quixotic mission to encourage investigators in Ukraine to look into both the origins of the Mueller investigation and dealings involving the Biden family. He has done so with the explicit blessing of President Trump, who considers the former vice president and 2020 candidate a top nemesis headed into a presidential election year.

“Seeking to enlist a foreign actor to interfere with an American election undermines our sovereignty, democracy, and the Constitution, which the President is sworn to preserve, protect, and defend,” Rep. Eliot Engel (D-NY), chair of the Foreign Affairs Committee, wrote to Pompeo.

“The President and his personal attorney now appear to be openly engaging in precisely this type of abuse of power involving the Ukrainian government ahead of the 2020 election.”

The Daily Beast first reported in June that Democrats on Capitol Hill were preparing an investigation into Giuliani that focused on whether the former mayor’s efforts in Ukraine worked against U.S. foreign policy interests. Earlier this month, the congressional committees formally announced their probe and said they would also look at Trump’s decision to temporarily withhold security assistance to Kiev.

That military assistance as well as Trump and Giuliani’s conversations with Ukraine about Biden are a part of an official whistleblower complaint filed with the director of national intelligence. Although the complaint is not public and is being withheld from Congress, it’s emerged that Trump asked Ukrainian President Volodymyr Zelenske to investigate Biden for his son’s business activities in the country.

“The conversation I had was largely congratulatory, with largely corruption, all of the corruption taking place and largely the fact that we don’t want our people like Vice President Biden and his son creating to the corruption already in the Ukraine,” Trump told reporters Sunday. Giuiliani has openly acknowledged he tried to convince Ukraine to look into the Bidens.

Engel demanded Pompeo respond by Thursday as to whether the State Department will cooperate with the congressional investigation.

Asked Monday if he’d agree to an interview with Congress, Giuliani tersely replied to The Daily Beast: “No, not [with] the corrupt ones like Schiff and Nadler.” He also cited attorney-client privilege between him and President Trump.

“If they want to come after me, I gladly accept it, because we could just make the Biden stuff bigger news,” Giuliani told The Daily Beast in June. “Do it! Give me a chance to give a couple speeches about it and hold a press conference. I’d love that…I think it’d be a fun fight. I’ll just compare it to all the things they’re not investigating…If they want, we can have a big fight over this.”