Former Republican congressman Joe Walsh made his 2020 primary challenge against President Donald Trump official on Sunday morning during an interview with ABC News’ George Stephanopoulos. And in the process he apologized for some of his most “Trumpian” statements over the past few years.

After making his case for why Trump is “completely unfit to be president” and he could be the “alternative” more traditional Republican voters have been craving, Walsh was forced to reckon with his own controversial record on This Week.

“You said you want to make the case against the president. The question is, are you the best messenger?” Stephanopoulos asked.

“I helped create Trump,” the right-wing radio host replied. “And George, that's not an easy thing to say.” As part of the “Tea Party class” in Congress, Walsh said he “wanted to shake Washington up” and sometimes “went beyond the policy and the idea differences, and I got personal, and I got hateful.”

“I said some ugly things about President Obama that I regret,” he added. “And it's difficult, but I think that helped create Trump. And I feel responsible for that.”

For much of the Obama administration, Walsh repeatedly pushed the same “birther” conspiracies that Trump did and, as the host pointed out, was calling Obama a Muslim as recently as December 2016. “Did you really believe he's a Muslim?” Stephanopoulos asked.

“God no. And I have apologized for that,” Walsh answered. “And that's not an easy thing to do, not at all.” He did not offer an apology for tweeting that Sen. Kamala Harris (D-CA) “can say dumb things” and get away with it because she’s a black woman, comments Stephanlopoulos called “textbook racism and sexism.”

Stephanopoulos neglected to ask if Walsh was sorry for endorsing arming toddlers on Sacha Baron Cohen’s Showtime series Who Is America?

“But think about the contrast, George,” Walsh added. “Again, I'm baring my soul with you right now on national TV. We have a guy in the White House who's never apologized for anything he's done or said. I think it's a weakness not to apologize. I helped create Trump. There's no doubt about that, the personal, ugly politics. I regret that. And I'm sorry for that.”