WASHINGTON — David Holmes, a career foreign service officer, told impeachment investigators Friday that he overheard a phone call between President Donald Trump and E.U. Ambassador Gordon Sondland in which the president asked Sondland if Ukraine would investigate the Bidens, a source with direct knowledge of his closed-door testimony said.

Holmes, counselor for political affairs at the U.S. embassy in Ukraine, confirmed what the acting ambassador to Ukraine, Bill Taylor, revealed Wednesday during the first open impeachment hearing. Taylor testified that an aide — Holmes — overheard Trump and Sondland on the phone during a lunch in Kyiv on July 26, the day after the call between Trump and Ukrainian President Volodymyr Zelenskiy at the heart of the House's inquiry.

Taylor said Holmes informed him that Trump could be heard asking about "the investigations," and that Sondland told Trump that the Ukrainians were ready to move forward.

Holmes told the three committees conducting the impeachment inquiry that on July 26, he went to lunch with Sondland in Kyiv with a staffer of Sondland’s and another staffer who worked at the U.S. embassy in Kyiv, according to the opening statement.

CNN first reported on Holmes' statement. Democrats are examining whether the Trump administration demanded two political favors from Ukraine — investigations into Trump's former Vice President Joe Biden and his son Hunter Biden, and into Ukraine's purported role in the 2016 U.S. election — in exchange for U.S. military aid.

Holmes said that during the lunch, Sondland said that he was going to call Trump to “give him an update,” and then did so on his mobile phone.

"I heard President Trump then clarify that Ambassador Sondland was in Ukraine. Ambassador Sondland replied, yes, he was in Ukraine, and went on to state that President Zelenskiy 'loves your ass.' I then heard President Trump ask, 'So, he’s gonna do the investigation?'" Holmes recounted, according to the statement. "Ambassador Sondland replied, that 'he's gonna do it,' adding that President Zelenskiy will do, 'anything you ask him to.'"

Holmes said he was able to hear the conversation because Sondland held the phone away from his ear due to how loudly the president was speaking, according to the statement. He told lawmakers he didn’t take notes of the conversation, but that he has a clear recollection of it, and that he immediately told Embassy staff about the call.

Holmes testified that after the call ended, Sondland told him that when it came to Ukraine, Trump only cares about "big stuff," such as the "Biden investigation" pushed by Trump attorney Rudy Giuliani.

Holmes appeared before Congress Friday evening under subpoena, an official working on the inquiry said, in light of an attempt by the State Department to block or limit his testimony.

Rep. Ted Lieu, D-Calif., characterized Holmes' account as "damning" after emerging from the deposition in the basement of the Capitol.

“He’s a career foreign service officer who entered during the George W. Bush administration. He is not partisan — he is simply telling the truth. Without going into detail [about] what he said, he does confirm what Ambassador Taylor said is true,” Lieu said of Holmes.

“He has first-hand knowledge of the conversation between Ambassador Sondland and the president of the United States,” Lieu added. “He overheard the conversation.”

In public testimony before the House Intelligence Committee Wednesday, Taylor told lawmakers that Holmes informed him the previous Friday about a phone conversation that he overheard between Sondland and the president.

“In the presence of my staff at a restaurant, Ambassador Sondland called President Trump and told him of his meetings in Kyiv. The member of my staff could hear President Trump on the phone, asking Ambassador Sondland about “the investigations.” Ambassador Sondland told President Trump that the Ukrainians were ready to move forward,” Taylor said in his opening statement, with Holmes being the member of his staff who heard the exchange.

“Following the call with President Trump, the member of my staff asked Ambassador Sondland what President Trump thought about Ukraine. Ambassador Sondland responded that President Trump cares more about the investigations of Biden, which Giuliani was pressing for,” Taylor continued.

Holmes’ closed-door deposition comes after the former ambassador to Ukraine, Marie Yovanovitch, provided testimony to the House Intelligence Committee during the second public impeachment hearing.