“So, he’s gonna do the investigation?” Trump asked, according to Holmes's testimony.

"He’s gonna do it,” Sondland replied.

The call, Holmes said, occurred at a restaurant in Kyiv on July 26, one day after Trump's now-famous phone conversation with Ukrainian President Volodymyr Zelensky in which Trump asked Zelensky for "a favor" in the form of investigations into former Vice President Joe BidenJoe BidenButtigieg surges ahead of Iowa caucuses GOP eager for report on alleged FBI surveillance abuse Biden leads among Latino Democrats in Texas, California MORE and the 2016 elections.

Both of those probes could have helped Trump politically, and the Democrats' impeachment inquiry is focused on whether Trump abused his office by recruiting a foreign leader for help in a U.S. election.

Trump's Republican allies have criticized many of the witnesses who've testified in the investigation, saying their accounts lean too heavily on second- or third-hand information and are therefore unreliable. Holmes's account was purportedly first-hand, and Democrats hailed his arrival in the Capitol.

"We always learn more when witnesses come in, and today we learned a lot more," Rep. Eric SwalwellEric Michael SwalwellKey takeaways from first public impeachment hearing Kent, Taylor say they're not 'Never Trumpers' after Trump Twitter offensive Live coverage: House holds first public impeachment hearing MORE (D-Calif.), a member of the Intelligence Committee, said Friday night as he left the closed-door deposition.

"The arrows continue to point in the direction of a shakedown scheme, led by the president of the United States [and] operated by agents like Rudy GiulianiRudy GiulianiTrump knocks testimony from 'Never Trumpers' at Louisiana rally Jordan calls Pelosi accusing Trump of bribery 'ridiculous' Giuliani under investigation for alleged campaign finance, lobbying breaches: report MORE, Gordon Sondland and Mick MulvaneyJohn (Mick) Michael MulvaneyTrump files to dismiss lawsuit from Bolton aide on impeachment testimony OMB official to testify in impeachment probe if subpoenaed after others refused Kent, Taylor say they're not 'Never Trumpers' after Trump Twitter offensive MORE," he continued.

On the July 26 call, Holmes testified, Sondland told Trump that Zelensky would do anything the president asked – including comply with the investigation requests – because the Ukrainian leader "loves your a--."

Holmes also testified that he asked Sondland after the call if it was true that Trump “did not 'give a shit about Ukraine.'”

Sondland responded that Trump only cares about "big stuff," Holmes testified. Holmes said he noted plenty of big things happening in Ukraine, including a five-year-old war with Russia in the east.

"He meant 'big stuff' that benefits the President, like the Biden investigation that Mr. [Rudy] Giuliani was pushing," Holmes said, paraphrasing Sondland.

Holmes said Sondland's cell phone was not on speaker mode, but he could nonetheless hear Trump's words because "the president's voice was very loud and recognizable."

The account was the latest twist in the fast-developing impeachment inquiry into Trump's handling of foreign policy in Ukraine. Just days ago, the Trump-Sondland phone conversation was not widely known, but on Wednesday, William Taylor, the top U.S. diplomat in Ukraine, testified publicly that Holmes relayed the story to him last week.

Holmes, the counselor for political affairs at the U.S. Embassy in Ukraine, is one of Taylor's top staffers in Kyiv.

Holmes was the 16th witness to be interviewed behind closed doors in the Capitol basement since Democrats began the private depositions on Oct. 3.

His appearance came on the heels of the testimony of another witness, Marie YovanovitchMarie YovanovitchLive coverage: Ex-Ukraine ambassador testifies in public impeachment hearing Ex-Trump Russia expert told lawmakers she's gotten death threats Giuliani lawyers up amid impeachment inquiry MORE, who appeared in public before the Intelligence Committee for roughly five hours earlier in the day on Friday.

Yovanovitch, the former U.S. ambassador to Ukraine, was deposed privately last month, but returned to Capitol Hill as the third witness to testify as part of the public hearing phase of the Democrats' impeachment inquiry.

The former ambassador, who was removed abruptly from Kyiv in May, painted a bleak picture of career diplomats fighting to salvage U.S.-Ukraine relations in the face of a shadow foreign policy, led by Giuliani, to secure business deals and political favors at all costs.

“How could our system fail like this?" she testified. "How is it that foreign corrupt interests could manipulate our government?”