WATCH: @MattGaetz exposes one of the Democrats' witnesses obsessions with impeachment. Feldman claims he was an "impeachment skeptic." Yeah right! pic.twitter.com/PTBuki1RH3 — Trump War Room (Text TRUMP to 88022) (@TrumpWarRoom) December 4, 2019

In his testimony before the House Judiciary Committee on Wednesday, Harvard Law Professor Noah Feldman declared under oath that he was an "impeachment skeptic" until the July 25 call between President Trump and the Ukraine president at the center of the Democrats' impeachment inquiry.

However, in a Vice magazine article in May 2017, noted Charlie Kirk in a tweet, Feldman said that Trump had committed impeachable acts.

And the professor wrote a piece for Bloomberg in March 2017 in which he claimed Trump risked impeachment over tweets he posted accusing President Obama of tapping his phones.

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On Wednesday, Feldman confirmed to the Democrats' counsel, Norm Eisen, that he had been "somewhat of an impeachment skeptic" at the time of the release of the special counsel report by Robert Mueller in April.

"What's changed for you, sir?" the attorney asked.

Feldman replied that it was the July 25 phone call in which Trump asked Ukraine President Volodymyr Zelensky to "look into" possible corruption in Hunter Biden's receipt of more than $3 million from a Ukrainian gas firm while his father spearheaded Ukraine policy.

In a Q&A in the 2017 Vice article, Feldman was asked if the president committed a crime in his White House conversation with then-FBI Director Jim Comey.

"What the president did is an outrage. It's impeachable, and obstruction of justice in the sense of being a 'high crime and misdemeanor,'" he said.

During the hearing Wednesday, Rep. Matt Gaetz, R-Fla., challenged Feldman's description of himself as an "impeachment skeptic" prior to the Ukraine phone call.

Gaetz cited Feldman's contention that "wiretap tweets" by Trump were impeachable along with a "Mar-a-Lago" ad and the president's accusations of "fake news."

The congressman also noted that Feldman wrote in an article in May titled "It's hard to take impeachment seriously now." In it, pointed out Gaetz, Feldman said that since the 2018 midterm election, House Democrats "have made it painfully clear that discussing impeachment is primarily or even exclusively a tool to weaken President Trump's chances in 2020."

Feldman then reiterated to Gaetz: "Until this call on July 25th, I was an impeachment skeptic. The call changed my mind, sir. And for good reason."

The Harvard professor testified alongside two other legal scholars called by the Democrats, Stanford Law professor Pamela Karlan and University of North Carolina Law Professor Michael Gerhardt.

The sole witness called by the Republicans contended impeaching Trump over the Ukraine allegations would be a historic mistake.

Jonathan Turley, a professor at George Washington University Law School, noted he did not vote for President Trump and has been critical of the president.

He warned against partisan rancor influencing what should be a constitutionally based process.

"If the House proceeds solely on the Ukrainian allegations, this impeachment would stand out among modern impeachments as the shortest proceeding, with the thinnest evidentiary record, and the narrowest grounds ever used to impeach a president," Turley said.