Democrats are heavily relying on an impeachment probe witness, Ambassador Bill Taylor, who did not use the infamous July 25 call to back his claim that President Donald Trump attempted to pressure Ukraine to investigate Joe Biden and his son in exchange for aid.

The July 25 call between Trump and Ukrainian President Volodymyr Zelensky is at the center of the impeachment probe. This week, House Speaker Nancy Pelosi (D-CA) released an impeachment inquiry fact-sheet mainly focused on alleged wrongdoings by Trump during the call.

Nevertheless, it appears Democrats are betting all their pro-impeachment chips on a claim unrelated to the July 25 call between Trump and Zelensky that ultimately triggered the impeachment. Taylor, whom TIME reported has “engendered respect from Democrats,” does not have first-hand knowledge of the conversation between Trump and Zelensky. He did not find out about the contents of the call until after it took place. Democrats and the mainstream liberal media, however, have praised his testimony.

An unnamed Democrat aide described the testimony to Vanity Fair as a “game-changer,” adding that Taylor is the “star witness” for lawmakers conducting the impeachment probe.

During his deposition Tuesday, Taylor highlighted conversations with other administration officials, not the July 25 call, as evidence of the alleged quid pro quo regarding Ukraine that he claimed took place. The conversations amount to internal administration discussions. As a result, there are no transcripts of those conversations to confirm or contradict Taylor’s characterization of what was said by the Democrat impeachment investigators’ “star witness,” Taylor.

Some of those conversations also took place after the “whistleblower” filed the complaint on August 12. The “whistleblower” accused Trump of pressuring Zelensky during the July 25 call to launch a probe into the Bidens in exchange for aid. Trump and Zelensky have denied the allegation.

In his opening remarks prepared for Tuesday’s deposition, Taylor cited conversations as evidence of an alleged quid pro quo:

During this same phone call [on September 1] I had with Mr. [Tim] Morrison [from the White House National Security Council], he went on to describe a conversation [U.S.] Ambassador [to the European Union Gordon] Sondland had with [Zelensky’s assistant Andriy] Yermak at Warsaw. Ambassador Sondland told Mr. Yermak that the security assistance money would not come until President Zelenskyy committed to pursue the Burisma investigation. I was alarmed by what Mr. Morrison told me about the Sondland-Yermak conversation. This was the first time I had heard that the security assistance — not just the White House meeting [with Zelensky] — was conditioned on the investigations.

…

On September 7, I had a conversation with Mr. Morrison in which he described a phone conversation earlier that day between Ambassador Sondland and President Trump. Mr. Morrison said that he had a “sinking feeling” after learning about this conversation from Ambassador Sondland. According to Mr. Morrison, President Trump told Ambassador Sondland that he was not asking for a “quid pro quo.” But President Trump did insist that President Zelenskyy go to a microphone and say he is opening investigations of Biden and 2016 election interference and that President Zelenskyy should want to do this himself.

Former Vice President Biden’s son, Hunter, served on the board of directors of the Ukrainian company Burisma, which has been linked to corruption.

Before filing the complaint, the “whistleblower,” in what appears to be a violation of U.S. law, shared his concerns about the call with the office of Rep. Adam Schiff (D-CA), the leader of the impeachment inquiry. So other government employees may have discussed “whistleblowers'” concerns about the call before and after the leaker filed the complaint, which stemmed from information provided by other officials, not first-hand knowledge.

Democrats pursuing the impeachment probe claim they are trying to determine whether or not Trump abused his power by demanding the investigation into the Bidens during the July 25 call. By heavily relying on Taylor’s testimony, the Democrats are seemingly moving away from the July 25 call at the center of the investigation.

Schiff and the House Democrats impeachment lawyer, Douglas Letter, have already indicated that the inquiry may move beyond the Ukraine-linked call on July 25.

The Democrats are treating Taylor’s claim of a quid pro quo in his opening remarks, which is neither based on first-hand knowledge nor is it derived to the July 25 call, as the sounding of the death knell for Trump’s presidency.

Taylor acknowledged in his opening remarks that he was not aware fo the July 25 call until after it took place, adding, “I did not see any official readout of the call until it was publicly released on September 25.”

“I received no readout of the call from the White House,” he added. “The Ukrainian government issued a short, cryptic summary.”

Reps. Lee Zeldin (R-NY) and Mark Meadows (R-NC), both of whom witnessed Taylor’s testimony, said that his claim of a quid pro quo “collapsed” when lawmakers questioned him during his deposition.

Democrat lawmakers have nevertheless described Taylor’s opening statement as “damning,” “devastating,” “explosive,” and “disturbing.”