Rudy Giuliani, President Donald Trump's personal attorney, said Sunday that Secretary of State Mike Pompeo was aware of his efforts to persuade Ukrainian authorities to investigate former Vice President Joe Biden.

Giuliani said he had recently confirmed that Pompeo knew he pushed for Biden to be investigated, adding to allegations that Trump pressured foreign officials to investigate his potential 2020 Democratic opponent for his own political gain.

After a week of major developments in the fallout of the scandal, House Democrats are zeroing in on Trump's inner circle as they pursue the impeachment inquiry over allegations that Trump pressured foreign officials to investigate his potential 2020 Democratic opponent for his own political gain.

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Rudy Giuliani, President Donald Trump's personal attorney, said Sunday that Secretary of State Mike Pompeo was aware of his efforts to persuade Ukrainian authorities to investigate former Vice President Joe Biden.

Giuliani said on CBS's "Face the Nation" that he had recently confirmed that Pompeo knew he pushed for Biden, who is a Democratic hopeful in the 2020 Election, to be investigated, adding to allegations that Trump pressured foreign officials to investigate his political opponent for his own political gain.

"Did Secretary of State Pompeo know you were doing these things? Did he ask you to do these things?" host Margaret Brennan asked.

"He did not," said Giuliani, the former mayor of New York City. "But when I talked to the secretary last week, he said that he was aware of it."

—Face The Nation (@FaceTheNation) September 29, 2019

Giuliani has been at the center of controversy since a bombshell whistleblower complaint was revealed that centered on a July 25 phone call between Trump and Ukrainian President Volodymyr Zelensky in which Trump repeatedly raised to Zelensky a potential investigation into former Vice President Joe Biden, a political rival for the 2020 presidential election.

After a week of major developments in the fallout of the scandal, House Democrats are zeroing in on Trump's inner circle as they pursue the impeachment inquiry over allegations that Trump pressured foreign officials to investigate his potential 2020 Democratic opponent for his own political gain.

Pompeo is currently facing subpoenas from chairmen of three House committees over his failure to produce documents related to Ukraine as five other State Department officials were scheduled for deposition.

Giuliani and other members of Trump's inner circle came into the spotlight after a memo released by the White House quotes Trump urging Zelensky to launch an investigation and instructing him to speak with US Attorney General William Barr and Giuliani.

Read more: Here's the truth about the allegations involving Joe Biden's son and Ukraine drummed up by Trump and Rudy Giuliani

The claims go back to a bombshell New York Times story published May 1 that revealed the former vice president had successfully gotten a Ukrainian prosecutor removed from office, which prompted concerns of a possible conflict of interest.

Despite the repeated confirmation that there has been no proven wrongdoing by the former vice president, Trump and Giuliani have drummed up allegations against the Bidens to obscure Giuliani's communications with Ukraine and growing concerns that Trump may have collaborated with a foreign power to gain political leverage.

After the report, Giuliani announced he was planning to travel to Ukraine to press president-elect Volodymyr Zelensky to pursue two investigations that could act as political leverage for Trump.

Giuliani eventually canceled his trip after facing widespread criticism for what appeared to be an attempt to push a foreign government to meddle in the 2020 US election, but Trump and his allies have continued claiming Biden was acting in his own personal interest.