Congressional Republicans on Monday continued their attack against Democrats’ impeachment inquiry into President Donald Trump – and this time, it involved one of their own.

At multiple points in Monday’s judiciary hearing, Republicans took pains to build skepticism around the testimony of European Union Ambassador Gordon Sondland, a Trump political appointee and a key actor in Trump’s personal attorney Rudy Giuliani’s attempts to convince Ukraine to open an investigation into Trump’s chief political rival.

The nearly ten-hour hearing was billed by Democrats as a vehicle for both parties to make their case about whether or not the President should be impeached. Daniel Goldman, Majority Counsel for the House Permanent Select Committee on Intelligence, told the committee that Trump’s actions towards Ukraine presented a “clear and present danger to our free and fair elections and to our national security.” But Minority Counsel Steve Castor argued that the Democrats’ inquiry was not legitimate, not only because it lacked the requisite evidence, but because they had been gunning to impeach Trump since he assumed office nearly three years ago.

As the hearing advanced into the early evening, it became clear that a key component of Republicans’ strategy was to sow doubts over the credibility of Sondland, who has played a starring role in the impeachment inquiry. Sondland, Castor said, was an “enigma” who repeatedly exaggerated his relationship with the President and his role in Ukraine policy.

A self-described lifelong Republican and million dollar Trump donor, Sondland told impeachment investigators last month that he was part of an operation, helmed by Giuliani and directed by Trump, to compel Ukraine’s new President, Volodymyr Zelensky, to investigate former Vice President Joe Biden’s connections with Burisma, the gas company that once employed his son Hunter as a board member. “Mr. Giuliani’s requests were a quid pro quo for arranging a White House visit” for Zelensky, Sondland said in his public testimony on November 20. “Mr. Giuliani was expressing the desires of the President of the United States, and we knew that these investigations were important to the President.”

He also told investigators that he had spoken directly with the President about the investigations, providing the most direct connection to Trump that Democrats were able to establish throughout the inquiry. Both of those admissions were not without controversy – they were not part of his original deposition and were only submitted after testimony prompted by subsequent witnesses – but were deemed explosive on both sides of the aisle. Ken Starr, the former independent counsel who led the investigation that ultimately resulted in Bill Clinton’s impeachment, said on Fox News that Sondland’s testimony was a “bombshell” that gave the Democrats exactly what they needed to proceed with articles of impeachment.

It was no surprise then, that Sondland figured prominently in Democrats’ 300-page report they released last week summarizing the findings of their investigation. Sondland’s name, as Republicans repeatedly noted on Monday, appeared in the report over 600 times.

Rep. Jim Jordan, one of Trump’s top attack dogs, repeatedly emphasized the fact that Sondland had revised his testimony, using the alterations to cast doubt on his credibility. “They relied on Ambassador Sondland. Why did they pick Sondland?” Jordan asked Castor.

“Its probably the best they got,” Castor replied.

“That’s the best they got?” Jordan asked incredulously. “The guy that had to file an addendum to his testimony? The guy had to file the clarification?”

An attorney for Sondland declined to comment. But Republicans’ denigration of Sondland – who is still working for the President as an Ambassador – was a stark departure from the way some had defended him earlier in the inquiry.

When the State Department initially blocked Sondland from appearing before Congress as part of the inquiry in October, Jordan told reporters he had “looked forward” to his testimony, because he thought he would deny any evidence of a quid pro quo with Ukraine. “We were looking forward to the Ambassador’s testimony,” Jordan said at the time. Later, when Sondland came to testify before the House Intelligence Committee last month, ranking member Devin Nunes preemptively apologized to him for what he said would be inevitable “smears” coming from the Democratic side of the dais.

Just a few weeks later, those smears were coming from an entirely new direction.

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Alana Abramson at Alana.Abramson@time.com.