Kris Kobach, the former Republican secretary of state of Kansas who is now running for the U.S. Senate, struggled to answer a basic question about racism from CNN’s Chris Cuomo on Tuesday night.

The two sparred over President Donald Trump’s spate of racist attacks on several Democratic lawmakers, all women of color, telling them to “go back” to their own countries. The women are U.S. citizens.

Kobach defended Trump and refused to characterize the comments as racist.

So Cuomo put him on the spot with a hypothetical.

“What would you do if the president said, ‘I am a racist, that’s why I said it’? What would you do?” Cuomo asked.

“Then I would not defend him because then there is no excuse for racism in America,” Kobach replied.

“Really?” Cuomo asked. “Would you still support him as president?”

That’s when Kobach struggled.

“Ummm,” he said after several awkward seconds of silence. “I don’t know. That would be a really tough [inaudible].”

“Really?” Cuomo shot back. “You have to think about it? You have to think about whether or not you would support a racist? Really?”

“I’d have to know who was running against him,” Kobach replied.

“A racist?” Cuomo said. “An admitted racist, you’d have to know more?”

“If he said he was a racist, then probably not, of course,” was the best Kobach could muster up.

“Kris, c’mon, man, it can’t be that partisan,” Cuomo said.

Kobach then dismissed the entire line of discussion as “ridiculous hypotheticals.”

See the full conversation below. The discussion about supporting an openly racist president begins at 5:40: