A conservative lawyer and friend of Brett Kavanaugh’s who has been instrumental in boosting his Supreme Court nomination backtracked after posting a detailed conspiracy theory on Twitter designed to discredit Christine Blasey Ford’s claim that Kavanaugh sexually assaulted her when they were in high school.

“I made an appalling and inexcusable mistake of judgment in posting the tweet thread in a way that identified Kavanaugh’s Georgetown Prep classmate,” the lawyer, Ed Whelan, tweeted Friday. “I take full responsibility for that mistake, and I deeply apologize for it. I realize that does not undo the mistake.”

I made an appalling and inexcusable mistake of judgment in posting the tweet thread in a way that identified Kavanaugh's Georgetown Prep classmate. I take full responsibility for that mistake, and I deeply apologize for it. I realize that does not undo the mistake. — Ed Whelan (@EdWhelanEPPC) September 21, 2018

On Thursday night, Whelan, the president of the Ethics and Public Policy Center, posted a series of tweets laying out a conspiracy theory suggesting that Blasey misidentified Kavanaugh in her accusation. Whelan claimed instead that a high school classmate of Kavanaugh’s assaulted Blasey, posting detailed information about the classmate.

He has since deleted the tweets.

Blasey rejected Whelan’s theory in a statement to The Washington Post, saying that she knew Kavanaugh and the classmate and once visited the latter in the hospital.

“There is zero chance that I would confuse them,” she said.

Republicans on the Senate Judiciary Committee, which may hear testimony from Blasey and Kavanaugh next week, sought to distance themselves from Whelan, who has advised on Kavanaugh’s confirmation process. Whelan is also friends with Leonard Leo, the president of the Federalist Society, which has played a crucial role in shaping conservative judicial nominations.

On Friday the White House said that it “had no knowledge” of Whelan’s theory before his Thursday night tweets.

Whelan told The Washington Post on Friday that he had “not communicated at all” with White House officials or Kavanaugh about the conspiracy theory.

Others have tried to defend Kavanaugh by similarly calling into question Blasey’s allegation and trying to discredit her.

Sen. Orrin Hatch (R-Utah) said this week that she may have been “mistaken” and that “clearly somebody’s mixed up.”

The Wall Street Journal editorial board this week posited that “mistaken identity is also possible,” and The Washington Post ran a piece by opinion columnist Kathleen Parker under the headline “Is There a Kavanaugh Doppelganger?”

After refraining from calling out Blasey directly, President Donald Trump on Friday questioned why she didn’t immediately call police after Kavanaugh’s alleged assault — continuing his pattern of attacking sexual assault accusers and suggesting that they are lying.