Top congressional Democrats are actively discussing opening a probe into Rudy Giuliani for his overseas political and consulting work, including a recent attempt to uncover dirt on former Vice President Joe Biden, a source with direct knowledge tells The Daily Beast.

The contours of a potential probe are still under consideration. But it would likely look at whether Giuliani’s relationships with foreign politicos interfered or intersected with American foreign-policy efforts.

Asked about the prospect of lawmakers investigating his foreign work, President Donald Trump’s lawyer had a defiant response: Bring it on.

“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. “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.”

The former New York City mayor insisted there was “nothing illegal or unethical about” any of his overseas trips or foreign work in the Trump era, and accused Democrats on Capitol Hill of “trashing the Constitution” and potentially engaging in the “biggest misuse” of congressional power “since Joe McCarthy.”

The news of a potential Giuliani probe comes as Democrats on the Hill are attempting to ramp up their investigations into President Trump. Several congressional committees, including judiciary and oversight, have called on former Trump officials to cooperate in their investigations. But the White House has stonewalled those efforts, refusing to acquiesce to witness-interview and document-production requests.

In response, House Judiciary Committee Chairman Jerry Nadler’s (D-NY) plans on introducing a resolution next week that would allow committees to sue the Trump administration and witnesses from the Mueller probe who do not comply with subpoenas, according to Democratic aides.

Giuliani would be, perhaps, the highest-profile investigative target to date. The president’s lawyer ultimately canceled his trip to Ukraine amid a backlash from Democrats and some disapproval from Republicans. But prior to that, he’d been open about his plans to go to the country to help uncover information on the origins of Special Counsel Robert Mueller’s probe and to encourage investigators to look into whether Biden had influenced a case that had been brought against his eldest son. As The New York Times first reported, Giuliani was seeking information on the involvement of Hunter Biden in an energy company owned by a Ukrainian oligarch. During the Obama administration, Vice President Biden had pushed for the dismissal of a Ukrainian prosecutor whose office controlled the inquiries into the company, on which Biden’s son had a seat on the board.

Giuliani, much of pro-Trump media, and President Trump himself had tried to frame the Biden story as a major political scandal. But it has since fizzled out. A Bloomberg News report noted that testimony from a former Ukrainian official and internal documents did not match the timeline or narrative that Biden had intervened to benefit Hunter. “There was no pressure from anyone from the U.S. to close [the] cases,” the former official said. “It was shelved by Ukrainian prosecutors in 2014 and through 2015.”

Speaking to The Daily Beast last month, the day before he nixed the trip, Giuliani said that he was briefing the president on his progress in Ukraine. He also noted that, based on their private conversations, he believed he had the full blessing of President Trump to keep digging on any actions Biden had taken. He mocked critics who accused him of “going after poor Joe.”

“The answers lie in Ukraine,” Giuliani insisted then. “This is what a defense lawyer does… I’m going after it like a hound dog.”

At the time, he compared his investigative jaunt to the kind of work done by Perry Mason, a fictional lawyer-detective from the 1950s and ’60s TV series.

In addition to Giuliani’s efforts in Ukraine, congressional Democrats are also said to be interested in the trips he has taken to Armenia and Romania.

Giuliani sent a letter to Romanian President Klaus Iohannis in August 2018 recommending changes to the country’s anti-corruption program. The contents of that letter diverged from the official State Department stance on the issue. He told Politico that he was paid for writing the letter by a global consulting firm. In October 2018, Giuliani appeared in Armenia, reportedly invited there by an Armenian businessman who lives in Russia. At the time, Giuliani said he was in Armenia as a “private citizen.” He spoke at a conference alongside a sanctioned Russian official.

“I hope they do investigate me for that because I would resist… and go on a rampage,” Giuliani said. “I’ll tell them I won’t comply [with a subpoena or any request] unless you investigate Biden first!”

He then added that such a probe, if launched by Democratic lawmakers, “would be harassment of the worst kind,” and that it would “also [be] interfering in my role as an attorney” for President Trump.