Former Attorney General Bill Barr said he is willing to testify against former President Trump at his Jan. 6 trial.

Barr, who was appointed by Trump, responded “of course” when asked on CBS’s “Face the Nation” if he would be willing to appear as a witness in Trump’s trial over federal charges related to alleged efforts to overturn the 2020 election. He declined to answer whether he was interviewed by the special counsel in connection to the federal investigation.

Barr has been a staunch critic of the former president since he resigned from his post shortly after the 2020 election. He noted that the case brought by special counsel Jack Smith was a “challenging” one, but that he does not think it “runs afoul of the First Amendment.”

When asked about his interactions with Trump and how he told the former president there was no evidence of election fraud, Barr said that his investigations into the fraud “satisfied” the conclusions.

“Well, I go through that in my book in painstaking detail, but on three occasions at least, I told him in no uncertain terms, that there was no evidence of fraud that would have changed the outcome,” he said.

Trump was indicted last week over his attempts to stay in power after losing the 2020 presidential election to President Biden. In a 45-page indictment, the Justice Department alleges Trump engaged in a campaign of “dishonesty, fraud and conceit” to obstruct a “bedrock function” of a democracy. He pleaded not guilty to the charges Thursday.