The top U.S. diplomat in Ukraine shook the Trump presidency to its core Tuesday.

In a riveting 15-page written statement to Congress, Chief of the U.S. Embassy in Kyiv William Taylor provided a birds-eye view of the scandal that has spawned an impeachment inquiry of President Trump.

Taylor described a growing sense of dismay since he agreed to take the post in Kyiv in May that the U.S.’s longtime bipartisan support for Ukraine was being undermined by Trump’s personal political considerations surrounding his re-election campaign.

In painstaking detail, reportedly gleaned from his extensive contemporaneous notes, Taylor recounted texts, phone calls, and meetings that laid bare the quid pro quo that President Trump has been vehemently denying.

Taylor testified that military aid to Ukraine and an in-person meeting between U.S. President Trump and Ukraine’s President Volodymyr Zelensky were contingent on Zelensky publicly announcing two investigations: one into Joe Biden’s son Hunter’s board seat at a Ukrainian gas company called Burisma, and another into allegations of Ukrainian interference in the 2016 elections. Both cases rely on unsubstantiated allegations and have been boosted by right-wing fever swamps in the U.S.

The testimony is a torpedo in Trump’s hull, coming after weeks of damaging revelations against which the President’s Republican allies have struggled to defend the administration. Taylor’s potentially historic testimony documents in meticulous detail how President Trump — abetted by political appointees — withheld military aid to Ukraine in a bid to pressure it into manufacturing political information that would be helpful to him in the 2020 elections.

Taylor said in his statement that through conversations with EU ambassador Gordon Sondland he came to understand that “everything” was dependent on Zelensky announcing an investigation.

Taylor made the statement during a deposition before the House, as it undertakes an impeachment inquiry into President Trump. The remarks were first obtained by the Washington Post.

“In August and September of this year, I became increasingly concerned that our relationship with Ukraine was being fundamentally undermined by an irregular, informal channel of U.S. policy-making and by the withholding of vital security assistance for domestic political reasons,” the statement reads.

Taylor wrote that when he first heard in July that the $250 million in military aid to Ukraine had been frozen, he realized “that one of the key pillars of our strong support for Ukraine was threatened.”

“The irregular policy channel was running contrary to the goals of longstanding U.S. policy,” the statement reads.

Taylor opened his testimony by laying out what happened chronologically.

He began by noting that his ousted predecessor — Ambassador Marie Yovanovitch — was “treated poorly” due to “political machinations both in Kyiv and in Washington.”

After her ouster, Taylor stepped into her role. “I feared that those problems were still present,” he said.

Taylor added concerns about “the role of Rudolph Giuliani.”

Describing the situation in Kyiv upon his arrival in June as “weird,” Taylor made note of “regular” and “highly irregular” channels through which the U.S. set policy toward Ukraine.

He said that his position gave him him control over the regular channel, but not the irregular one. That irregular channel, Taylor said, included “then-Special Envoy Kurt Volker, Ambassador Sondland, Secretary of Energy Rick Perry” and Rudy Giuliani.

“Although this irregular channel was well-connected in Washington,” Taylor wrote, it appeared to exist to circumvent the State Department.

Taylor pegged the birth of the so-called “irregular channel” — known elsewhere as the “three amigos” — to May 23, when Volker, Perry, and Sondland briefed Trump after returning from Kyiv where they had attended Ukrainian President Volodymyr Zelensky’s inauguration.

Once in Kyiv, Taylor said that he began to notice many things were amiss. An attempt to arrange a meeting between Trump and Zelensky hit an unexpected roadblock. On June 27, the statement reads, Sondland told Taylor over the phone that Zelensky “needed to make clear” that he wasn’t blocking any “investigations.”

Taylor added that in a conversation ahead of a call scheduled with President Zelensky on June 28, Volker said that he planned on being clear about “what President Zelensky should do to get the White House meeting.”

Taylor noted that he wrote a memo on June 30, memorializing the call.

He went on to say that he first heard about a delay in military aid to Ukraine on July 18, from an anonymous Office of Management and Budget official who announced the delay off-screen during a video conference call.

“All the OMB staff person said was that the directive had come from the President to the Chief of Staff to OMB,” Taylor’s statement reads.

Taylor recounted an Aug. 27 conversation he had with then-National Security Adviser John Bolton during a visit to Kyiv. Taylor said that he expressed concern about the aid being withheld to Bolton, who recommended that Taylor send a cable directly to Secretary of State Mike Pompeo. In that cable — sent on Aug. 29 — Taylor told Pompeo that “he could not and would not defend such a policy.”

Taylor added that Ukrainian official Andriy Yermak — who met with Giuliani in Spain on Aug. 2 — asked him about why the military aid had been withheld. “I was embarrassed that I could give him no explanation,” Taylor wrote.

In its recounting of events, the statement begins to rely on information that Taylor heard from National Security Council aide Tim Morrison, starting with a phone call on Aug. 22. In a later phone call, Morrison relayed to Taylor interactions that occurred between U.S. and Ukrainian officials at a Sept. 1 meeting in Warsaw.

In one such interaction, the statement reads, Sondland purportedly told Yermak that the military aid “would not come until President Zelensky committed to pursue the Burisma investigation.”

Taylor then texted Sondland, asking whether “we [are] now saying that security assistance and [a] WH meeting are conditioned on investigations?” Sondland asked Taylor to call him, and the pair spoke over the phone.

Sondland, Taylor said, explained that Trump had said he wanted Zelensky “to state publicly that Ukraine will investigate Burisma and alleged Ukrainian interference in the 2016 U.S. election.”

Taylor added that Sondland admitted he had made a mistake when he had tied a meeting with Trump to investigations. Not only was a meeting with Trump dependent on Zelensky announcing the investigations, he now explained, but, Taylor wrote, “‘everything’ was dependent on such an announcement, including security assistance.” Sondland purportedly told Taylor that he wanted to put Zelensky “in a public box” by making the statement.

Another, alternative possibility purportedly came up on the call: Attorney General Bill Barr and Ukraine’s general prosecutor would make a joint statement about investigations into potential interference in the 2016 elections. That did not come to fruition.

Taylor noted that even though he did not see a transcript of Trump’s infamous July 25 call with Zelensky until it was publicly released, he had understood for a long time that “‘investigations’ was a term that Ambassadors Volker and Sondland used to mean matters related to the 2016 elections, and to investigations of Burisma and the Bidens.”

He added that President Zelensky had briefly agreed to do a CNN interview during a conversation with Sondland, where the Ukrainian leader would make an unspecified “public statement” that would “clear things up.”

Though that interview does not appear to have occurred, Taylor noted a conversation he had about the proposed exchange with Sondland. The EU Ambassador purportedly told Taylor that “President 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,” the statement reads. Taylor added that Volker used “the same terms” a few days later, eventually prompting Taylor’s text to Sondland in which he called the withholding of aid “crazy.”

Read the statement here: