John Dickerson fact-checked Sen. Ted Cruz at the Republican debate Saturday night. The audience didn't love it.

Here's what happened. Republican candidates — including Sen. Ted Cruz — think President Barack Obama should leave the nomination of Justice Antonin Scalia's successor to the next president. So Dickerson asked if Cruz would be willing to abide by the same restriction himself.

"Where do you set that date if you're president?" Dickerson asked. "Does does it begin in election year, in December, November, September? And once you set the date, when you're president, will you abide by that date?"

Cruz argued that there's "80 years of precedent" of not confirming Supreme Court justices in an election year. In fact, Justice Anthony Kennedy was confirmed in an election year by a Democratic Congress. Dickerson tried to fact-check Cruz in real time, and the audience was not having it.

"Kennedy was confirmed in '88," Dickerson said.

"In '87," Cruz said. (Kennedy was nominated in 1987 and confirmed in 1988.)

"That's the question, is it appointing or confirming?"

"In this case it's both. If I could finish —" Cruz started.

"I want to get the facts straight for the audience," Dickerson said. The audience promptly booed. "But I apologize."