WASHINGTON – Secretary of State Mike Pompeo acknowledged Wednesday he was listening in on the controversial phone call between President Donald Trump and Ukraine's leader, Volodymyr Zelensky – a conversation that sparked the House Democrats' impeachment inquiry.

"I was on the phone call," Pompeo told reporters at a news conference in Rome. It marked the first time Pompeo has publicly disclosed his own knowledge of allegations that Trump pressured Zelensky for damaging information on former Vice President Joe Biden.

Pompeo had previously side-stepped questions about Trump's dealings with Zelensky and said he was not familiar with the details of a whistleblower complaint sparked by the July 25 call. The Trump-Zelensky call and the whistleblower complaint are now at the center of an impeachment inquiry examining whether Trump sought foreign interference in the 2020 election.

That phone call prompted a whistleblower to file an anonymous complaint alleging that Trump was "using the power of his office to solicit interference from a foreign country in the 2020 U.S. election," according to the complaint.

At the news conference in Rome, Pompeo did not answer a question about whether Trump's remarks to Zelensky raised any red flags for him. Instead, he talked broadly about U.S. policy toward Ukraine, which he said has been "remarkably consistent" and focused on two goals: countering Russian aggression against the eastern European ally and helping Ukraine fight its endemic corruption.

Pompeo's remarks came a day after he engaged in a high-stakes confrontation with House Democrats over their demands to depose five State Department employees as part of the impeachment inquiry. Democrats are seeking documents and interviews with Trump officials who could shed light on the State Department's role in connecting Rudy Giuliani, Trump's personal lawyer, with Ukrainian government officials.

For months, Giuliani has been pressing the Ukrainians for damaging information on Biden and his son, Hunter Biden, whose sat on the board of a Ukrainian energy company when Biden was Obama’s No. 2. Trump and Giuliani have alleged wrongdoing by the Bidens, but Ukrainian officials have said they have not found any evidence to support those charges.

On Tuesday, Pompeo pushed to delay testimony by five State Department officials who House Democrats have asked to depose. He accused Democrats of trying to "intimidate" and "bully" career professionals in their quest to impeach Trump.

Democrats responded by accusing Pompeo of "stonewalling" the impeachment inquiry and said he may be involved in a "blatant cover-up." They escalated those charges Tuesday night amid new reports from ABC News and CNN that the State Department's inspector general wanted to brief lawmakers on an "urgent" concern related to Ukraine.

A spokeswoman for the State Department's watchdog has not responded to a request for comment.

On Wednesday, the top Democrat on the Senate Foreign Affairs Committee called on Pompeo to recuse himself from Ukraine-related matters.

“The American people need to have confidence that the nation’s chief diplomat is making decisions based on the national interest – not to advance a partisan political agenda," said Sen. Bob Menendez, D-N.J. "Recusal is the only option at this point to prevent further erosion of the integrity of U.S. foreign policy.”

Rep. Eliot Engel, D-N.Y., who leads the House Foreign Affairs Committee, said Pompeo should not have any role in the executive branch's response to the impeachment inquiry.

"He's now part of the investigation," Engel said.

The chairman of the House Intelligence Committee, Rep. Adam Schiff, said Democrats are "deeply concerned" about Pompeo's effort to delay the depositions and said any effort to interfere with the impeachment inquiry would be considered evidence of "obstruction of justice." Schiff also said any effort to conceal or deny document requests would carry the "adverse inference" that the underlying "allegations are correct."

Pompeo has said State Department officials acted appropriately on the Ukraine matter, although he seemed to leave himself some leeway for new revelations.

"To the best of my knowledge, so from what I’ve seen so far, each of the actions that were undertaken by State Department officials was entirely appropriate and consistent with the objective that we’ve had certainly since this new government has come into office," Pompeo told reporters at a news conference last week.

Until this week, Pompeo had avoided directly answering questions about his role in the Ukraine scandal.

More:Pompeo may be involved in 'blatant cover-up', Democrats charge in new salvo aimed at top diplomat

Asked about the State Department's dealings with Ukraine last week, Pompeo responded: "I haven’t had a chance to actually read the whistleblower complaint yet. I read the first couple of paragraphs and then got busy today. But I’ll ultimately get a chance to see it. If I understand it right, it’s from someone who had secondhand knowledge."

On Sept. 22, as the Ukraine allegations were first emerging, Pompeo did not answer a question about whether he had pressed Ukrainian officials to investigate Biden. In an interview with CBS’ Face the Nation, Pompeo said he has spoken with Ukraine’s foreign minister a couple of times but offered only a vague description of those conversations.

“We talk about the important relationship between our two countries and how we can make Ukraine stronger and have great economic commerce between our two great nations,” Trump’s secretary of state said.

More:Trump claims impeachment inquiry against him is a 'coup' designed to 'take away Power of the People'