President Trump's personal attorney, Rudy Giuliani, said on Sunday that Secretary of State Mike Pompeo had told him he was aware of his unorthodox diplomatic campaign to pressure Ukraine's government to dig up political dirt on former Vice President Joe Biden and his son, Hunter.

"I did not do this on my own. I did it at the request of the State Department and I have all of the text messages to prove it. And I also have a thank you from them from doing a good job," Giuliani said on "Face the Nation." "When I talked to the secretary last week, he said he was aware of it."

Giuliani's claim on Sunday echoes recent allegations that he and others, including a whistleblower whose compliant is at the center of an impeachment push against Mr. Trump, have made about the State Department's supposed involvement in his behind-the-scenes outreach to Ukraine, a staunch U.S. ally dealing with a Russian-backed insurgency in its eastern territory.

Along with denouncing a call in July in which Mr. Trump pressed Ukrainian President Volodymyr Zelensky to investigative the Bidens, the whistleblower in the complaint said senior State Department officials — including the former U.S. envoy to Ukraine, Kurt Volker — reached out to Giuliani to "contain the damage" of his rogue communication with the Ukrainian government.

Giuliani has said the State Department's involvement in his outreach to the Ukrainian government started in July, when he said Volker connected him with a top Zelensky aide. Soon after meeting with the aide, Andriy Yermak, Giuliani said he called both Volker and the U.S. Ambassador to the European Union, Gordon Sondland, to brief them on his conversation.

After that phone call, Giuliani said he participated in a "full debriefing" on the matter on August 12.

The State Department last week acknowledged Volker's role in securing Giuliani's meeting with Yermak, but a spokesperson denied that Mr. Trump's lawyer spoke "on behalf" of the administration. After his involvement came to light, Volker resigned as special envoy to Ukraine, a part-time volunteer position. Congressional Democrats, now operating under the umbrella of an impeachment inquiry, have announced they intend to compel him to testify on Capitol Hill.

Giuliani said neither Volker nor Sondland mentioned Pompeo's name during their conversations, but that he later found out America's chief diplomat had been informed about this outreach.

"However, when I spoke to the secretary last week, I said, 'Are you aware of this?' and he said, 'Yes, I know about this,'" Giuliani said.

Giuliani said he believes there are "many people" at the State Department who were concerned about Volker's involvement in his outreach to Ukraine. He said officials are trying to distance themselves from his effort.

"The State Department is running away from me," he added.