Rudy Giuliani acknowledged on Thursday that he had asked top Ukrainian officials to investigate former Vice President Joe Biden, an admission that comes as Capitol Hill Democrats investigate whether President Donald Trump and his personal lawyer are pressuring Ukraine’s government to dig up dirt on a 2020 election rival.

“So you did ask Ukraine to look into Joe Biden?” CNN’s Chris Cuomo asked Giuliani in an interview on Thursday evening.

“Of course I did,” Giuliani shot back.

His comments come amid House Democrats’ intensifying look at allegations that Giuliani and Trump were squeezing Ukraine’s recently elected president, Volodymyr Zelensky, to reopen an investigation of a company connected to Biden’s son Hunter. The chairmen of the House Intelligence, Foreign Affairs and Oversight committees wrote to White House counsel Pat Cipollone last week demanding all documents that reference the allegations against Hunter Biden, as well as the transcript of a July 25 call between Trump and Zelensky.

A Ukrainian readout of the call indicates that Trump indicated Ukraine could improve its image in part by completing the “investigation of corruption cases, which inhibited the interaction between Ukraine and the USA.”

The House investigation and Giuliani’s comments take on added significance in light of new reports in The New York Times and The Washington Post that suggest a whistleblower complaint about Trump, filed on Aug. 12 by a member of the intelligence community, centers on Ukraine.

An intelligence community watchdog deemed the complaint credible and “urgent,” a designation that typically triggers an automatic referral to Congress. But the nation’s top intelligence official, acting Director of National Intelligence Joseph Maguire, intervened to prevent it from reaching the Capitol, instead referring it to the Justice Department, which determined that the matter was privileged.

Lawmakers say they haven’t learned the substance of the whistleblower complaint and can’t confirm whether media reports about it are accurate. But Democrats on the House Intelligence Committee are sounding the alarm, claiming that the effort to prevent Congress from accessing the whistleblower’s account appears to be an effort to shield high-level wrongdoing by the president or his top advisers.

Giuliani has for months encouraged Ukrainians to advance investigations into whether Biden’s diplomatic work with Ukraine intersected with his son’s role in a gas company owned by a Ukrainian oligarch. He has also sought an investigation into whether Ukrainian officials worked to harm Trump’s 2016 election bid.

“In the course of investigating that, I found out this incredible story about Joe Biden, that he bribed the president of the Ukraine in order to fire a prosecutor who was investigating his son,” Giuliani said on CNN on Thursday. “That is an astounding scandal of major proportions which all of you have covered up for about five or six months.”

Democrats have noted that within days of Trump’s call to Zelensky, Giuliani met one of the Ukrainian president’s aides in Spain, a meeting that the State Department later said had been facilitated by the American ambassador to Ukraine, Kurt Volker. Around the same time, POLITICO reported that Trump held up a $250 million package of military aid to Ukraine, meant to shore up the country’s defenses against neighboring Russia.

“If the President is trying to pressure Ukraine into choosing between defending itself from Russian aggression without U.S. assistance or leveraging its judicial system to serve the ends of the Trump campaign, this would represent a staggering abuse of power, a boon to Moscow, and a betrayal of the public trust,” the three committee chairmen, Reps. Adam Schiff, Elijah Cummings and Eliot Engel, wrote.

After Giuliani’s interview, Sen. Chris Murphy (D-Conn.) recounted a recent meeting with Zelensky in which he characterized the Ukrainian leader as very attuned to Giuliani’s demands and Trump’s handling of Ukraine’s military aid.

“I told him it was best to ignore requests from Trump’s campaign operatives. He agreed,” Murphy said on Twitter

“I don’t know what is in the whistleblower complaint,” he continued, “but it was clear to me that Ukraine officials were worried about the consequences of ignoring Giuliani’s demands. And of course they were. That’s why presidents shouldn’t have their campaigns talking to foreign leaders.”