President Donald Trump speaks as Secretary of State Mike Pompeo looks on during a Cabinet meeting in the Cabinet Room of the White House on August 16, 2018 in Washington, DC.

A senior American diplomat stationed in Ukraine's capital has told the House Intelligence Committee he'd never seen anything in his career like a July 26 phone call he witnessed between President Donald Trump and Gordon Sondland, the U.S. Ambassador to the European Union, in which the two men discussed investigations that Trump wanted Ukraine to launch.

In newly released testimony Monday night, David Holmes, a political affairs officer at the U.S. embassy in Kyiv, says he was shocked as he watched Sondland phone the president directly from an unsecured cell phone.

"I've never seen anything like this, someone calling the President from a mobile phone at a restaurant, and then having a conversation of this level of candor, colorful language," Holmes told investigators during his closed door deposition on Friday. "There's just so much about the call that was so remarkable that I remember it vividly."

In an opening statement that was released over the weekend, Holmes had described listening to Trump loudly ask Sondland over the phone if Ukrainian President Volodymyr Zelenskiy was "going to do the investigation." Sondland confirmed that he was.

After the call was over, Holmes said he asked Sondland, "Is it true the President doesn't give a shit about Ukraine?" According to the newly released transcript, Sondland responded, "Nope, not at all, doesn't give a shit about Ukraine." Sondland then explained that Trump only cared about "big stuff that matters to [Trump], like this Biden investigation that Giuliani is pushing."

According to Holmes' testimony, on that same call, Sondland and Trump also discussed the legal case of American rap artist, A$AP Rocky, who had been arrested in Sweden in late June and charged with assault after an altercation at a nightclub.

Trump appeared to be considering how much to intervene in the case, Holmes said. Sondland advised the president to, "wait until after the sentencing or it would only make it worse." Instead, Trump should, "let [Rocky] get sentenced, play the racism card, and give him a ticker-tape when he comes home," Holmes quoted Sondland as having told the president.

The entire event was so extraordinary, Holmes said, that he immediately reported it to his boss at the embassy. "You're not going to believe what I just heard," Holmes recalled telling his supervisor.

Sondland is scheduled to testify in public before the House Intelligence Committee on Wednesday. In his closed door deposition last month, Sondland failed to mention the July call with Trump that Holmes witnessed. Sondland also initially insisted he was largely unaware of Trump's pressure campaign on Ukraine to investigate the Bidens, although he later amended his testimony.

Sondland's July 26 phone call with Trump is expected to be a major topic of discussion during his hearing on Wednesday.

House Democrats are probing whether the president abused his powers by withholding aid to Ukraine in order to pressure the country's newly elected president to launch investigations into a son of former Vice President Joe Biden, and a debunked conspiracy theory about the 2016 election.

The Intelligence Committee also released testimony Monday from another State Department official, Under Secretary of State for Political Affairs David Hale.

In it, Hale described an intense effort last spring, by Secretary of State Mike Pompeo, to determine who was behind a media campaign to tarnish the then-U.S. Ambassador to Ukraine, Marie Yovanovitch.

Pompeo's efforts included two previously unreported calls that the secretary made to Trump's personal attorney, Rudy Giuliani, in late March. Hale also said he believed Pompeo had spoken to Fox News Channel host Sean Hannity about the attacks, which Hannity had featured on his nightly program.

Hannity has publicly denied ever speaking to Pompeo about Yovanovitch.

Hale also said that when he was first told that Giuliani was fueling the attacks, he couldn't believe it.

"I found it very hard to understand why a President of the United States would do it that way, when he can just — I mean, all Ambassadors are Presidential appointees, they serve at the pleasure of the President, so it didn't — it didn't add up to me," he said.

Over time, however, Hale came to understand that Giuliani was playing a major role in the campaign to remove Yovanovitch, which was ultimately successful.

Neither the White House nor the State Department had any immediate response Monday night to the new details contained in Hale's and Holmes' testimonies.

Both State Department officials are scheduled to testify in public this week before the Intelligence Committee — Hale on Wednesday afternoon at 2:30 p.m., and Holmes on Thursday morning, starting at 9:00 a.m.