House Speaker Paul Ryan on Tuesday slammed Donald Trump for questioning a judge’s fairness because of his “Mexican heritage,” calling the remarks “the textbook definition of a racist comment.”

Ryan, introducing an anti-poverty program in Washington, DC, said Trump’s comments were undermining the GOP’s efforts to deliver a positive message to voters.

“I disavow those comments. I regret those comments he made. It’s absolutely unacceptable,” the Wisconsin Republican said.

But he stood by his support for the real estate mogul, adding, “Do I think Hillary Clinton is the answer? No I do not.”

Ryan said Trump offended Hispanics with his comments about Judge Gonzalo Curiel, who is overseeing a class-action civil suit filed by students of Trump’s now-defunct Trump University, which the students called a scam.

Trump said the Indiana-born judge was not qualified to preside over a case because his parents were born in Mexico, and would hold Trump’s promise to build a border wall against him.

New Jersey Gov. Chris Christie, an early Trump supporter, rushed to the candidate’s defense.

“I’ve said this before, that I know Donald Trump, I’ve known him for 14 years, and Donald Trump is not a racist,” Christie said. “The allegations that he is are absolutely contrary to every experience that I’ve had with him over the last 14 years, so we’re going to end it there.”