Republicans’ most fruitful line of attack during the first day of congressional impeachment hearings for Donald Trump has put even more pressure on a forthcoming witness who has flailed under it thus far: donor-turned ambassador Gordon Sondland.

As two senior State Department officials spent nearly six hours recounting their alarm with an effort by Trump’s allies that they said undermined U.S. national interests in favor of promoting the president’s re-election, Republicans on the House Intelligence Committee repeatedly pointed out that neither witness had interacted with Trump or key deputies like White House Chief of Staff Mick Mulvaney or personal attorney Rudy Giuliani.

But a critical future witness had: Sondland, the U.S. ambassador to the European Union. Sondland, however, has reversed himself on central aspects of his participation in a shadow foreign policy effort—reversals that have put Trump in a worse position. And he testifies, publicly, next Wednesday.

His appearance gained more importance on Wednesday after Ambassador Bill Taylor revealed new details about a July 26 phone call between the president and Sondland, overheard by a Taylor staffer in Kyiv. Taylor told legislators that one of his staffers was at dinner with Sondland when Trump called. During the call, the staffer relayed to Taylor, Trump himself instructed Sondland to press the Ukrainians on delivering “the investigations.” The call came one day after Trump’s fateful phone call with Zelensky in which the U.S. president asked for “a favor.”

Sondland, Taylor recounted, said the Ukranians were ready to “move forward.” When the call ended, the Taylor staffer asked what Trump thought of Ukraine—to which Sondland replied that the president “cares more about the investigations of Biden.”

Sondland’s omission of that important detail in his Oct. 17 deposition—which was later amended to clarify his impression of a Trump quid pro quo—only adds to Democrats’ desire to cross-examine him. Aides and lawmakers predicted the ambassador would face withering questioning, probably from both sides.

“He should be able to tell us the contents of that conversation,” said Rep. Joaquin Castro (D-TX), a member of the House Intelligence Committee. “And he should tell us the truth. He owes us the truth, but more than that, he owes the American people the truth.”

Sondland’s lawyer declined to comment.

Throughout the summer of 2019, Sondland, who had described himself as Trump’s point person on Ukraine, had on several occasions described by numerous witnesses pressed aides to Ukrainian President Volodomyr Zelensky to commit, publicly, to investigating a gas firm tied to Trump political adversary Joe Biden and a conspiracy theory that Ukraine and not Russia interfered in the 2016 election.

Sondland, in a now-famous text message to Taylor, one of the two witnesses before the House on Wednesday, initially insisted the administration was not conditioning the release of $400 million in frozen U.S. military aid—as well as the prospect of a coveted White House meeting for Zelensky—on investigating Trump’s political enemies. But after the House intelligence, foreign affairs and oversight committees began investigating Sondland’s role, the hotel magnate and novice diplomat admitted that he told the Ukrainians “resumption of the U.S. aid would likely not occur until Ukraine provided the public anticorruption statement that we had been discussing.”

Taylor, who dissented from Sondland’s efforts—which were aided by Giuliani, ex-Ukraine special envoy Kurt Volker, Mulvaney and Energy Secretary Rick Perry—put Sondland under additional pressure during the first day of hearings.

Additionally, in a deposition last month, Taylor said that Sondland told him on a Sept. 8 phone call that the diplomat, then alarmed about the frozen military aid, needed to understand that Trump is a businessman. “When a businessman is about to sign a check to someone who owes him something, he said, the businessman asks that person to pay up before signing the check,” Taylor quoted Sondland as saying.

Sondland, in his depositions to the impeachment inquiry, had said he couldn’t recall many pivotal details about what Taylor had called a “highly irregular” channel at cross-purposes with official U.S. policy on assisting Ukraine. As October wore on, that became a tenuous position for Sondland—who had never before faced sustained congressional scrutiny—as multiple witnesses described their interactions with Sondland in detail, in some cases providing text messages and emails.

Volker, who with Sondland and Perry made up the “three amigos” of the shadow diplomatic channel, will testify publicly on Tuesday.

Ironically, Giuliani, the president’s personal lawyer who remains at the center of the Trump-Ukraine scandal, had previously downplayed Sondland’s role in the shadow campaign to influence the Ukrainian government.

In September, the former New York City mayor revealed to The Daily Beast that Sondland was indeed one of the diplomats who he had briefed on his progress, but insisted that Sondland was hardly the “main one,” and that they’d only spoken on a couple of conference calls. In fact, Giuliani had claimed that the first time he spoke to Sondland was a surprise—that he had patched himself into a call to discuss Ukraine matters and unexpectedly found that Sondland was also on the line and getting roped into the scheme.

Still, Sondland’s perceived closeness with the president and Ukraine could be further emphasized on Friday when former U.S. ambassador to Ukraine Marie Yovanovitch is slated to testify to the committee. In her deposition last month, Yovanovitch said she sought Sondland’s advice when it became clear she was being targeted by Giuliani and his associations. According to Yovanovitch, Sondland advised her to “tweet out there that you support the President, and that all these are lies and everything else.”

As Taylor and Deputy Assistant Secretary of State George Kent testified, Republicans attacked their credibility. Ranking Intelligence Committee Republican Devin Nunes (R-CA) went the furthest, calling them “remarkably uninformed” about statements made by now-former Ukranian officials in 2016 deriding Trump. (Nunes implied that meant the Ukranians interfered in the election, something U.S. intelligence agencies, who assessed Russian interference instead, have never credited.) Rep. Jim Jordan (R-OH) told Taylor he was “wrong” to understand U.S. security assistance and the White House visit were conditioned on Ukraine delivering the investigations, since Trump ultimately released the aid on Sept. 11—although that was after Congress learned that a whistleblower had raised alarm over the Trump-Zelensky phone call.

Taylor’s source for his understanding, he shot back to Jordan, was Gordon Sondland.

Rep. Tom Malinowski (D-NJ), who sits on the House Foreign Affairs Committee, said the Taylor’s information about the call showed how close Sondland was to the operation.

“I think it’s all the more clear that Sondland was doing everything in coordination with the president and the president saw Sondland as the instrument of his policy of getting these investigations from the Ukrainians,” he said.

After the hearing, Trump’s team emphasized that Kent and Taylor were irrelevant witnesses who were never in the loop with the president and attacked them as “bureaucrats” who were shanking the president for disagreeing with them on policy.

“Today we heard from Democrats’ hand-picked star witnesses, who together were not on the Ukraine phone call, did not speak directly to President Trump, got third-hand hearsay from one side of a different phone call in a restaurant, and formed opinions based on stories in the pages of the New York Times,” Trump campaign manager Brad Parscale said in a statement. “We hate to break it to these unelected, career government bureaucrats who think they know best: the President of the United States sets foreign policy, not them.”

Throughout the impeachment inquiry’s big day, numerous Trumpworld figures and top administration officials—including the president—used their social media accounts as tools of rapid-response and insta-rebuttal against the Democratic inquisitors. Senior officials on the Trump reelection campaign, such as National Press Secretary Kayleigh McEnany, quickly clipped and quoted in real time their GOP allies on Capitol Hill who were grilling the witnesses, in wall-to-wall denunciation of “the Democrat lies.”

“Do you not stand with [President] Trump in the Fake Impeachment Hoax? He needs you in this fight, friend,” the 2020 Trump campaign texted to supporters as the hearing wrapped. “Donate for a DOUBLE-MATCH NOW,” the message added, as campaign brass aggressively fundraised off of Trump’s impeachment woes on Wednesday.

The president, for his part, made a perhaps futile attempt to counter-program the public hearing—by hosting GOP senators and Turkish strongman Recep Tayyip Erdogan in the Oval Office for an awkward make-up session.

Shortly after both the Oval summit and the Hill hearing had concluded, Trump and Erdogan held a joint press conference at the White House, during which the pair traded words of flattery and discussed the Middle East and relations between their two countries. President Trump, of course, made time to riff on Wednesday’s “witch hunt” that he said should never have been allowed to proceed. He reiterated his desire to have the anonymous whistleblower outed, and called the public hearing a “joke.” Trump also noted that it was a shame they had to “waste this gentleman’s time”—meaning his friend Erdogan—talking about it.

It wasn’t long before Sondland was brought up there, as well.

Asked by a reporter about the story Taylor relayed from his aide during testimony, Trump denied knowing anything about it.

“I know nothing about that, first time that I heard it,” he said. “The one thing I’ve seen is that Sondland said was that he did speak to me for a brief moment. I said no quid pro quo under any circumstances. And that's true. I never heard this.”

He added, “In any event, it is more secondhand information, but I've never heard it.”

Additional reporting Erin Banco, Betsy Swan