CBS cut off the mics after JD Vance objected to a fact-check of his claims about immigration during the vice presidential debate on Tuesday.

After Vance said that “millions of illegal immigrants” had overwhelmed cities like Springfield, Ohio, moderator Margaret Brennan noted that the issue in Springfield has to do with Haitians who immigrated legally. Vance objected, saying the fact-check was against the agreed ground rules.

“Since you’re fact-checking me, I think it’s important to say what’s actually going on,” Vance said.

Brennan tried to move on to a new topic, but Vance pressed ahead, talking about the asylum system. After a few moments, and some crosstalk from Tim Walz, Brennan and co-moderator Norah O’Donnell stepped in, and the microphones were shut off.

“The audience can’t hear you because your mics are cut,” Brennan said. “We have so much we want to get to.”

Fact-checks were a contentious issue for the Republican ticket after the ABC debate on Sept. 10 between Kamala Harris and Donald Trump. The moderators in that debate intervened repeatedly to correct Trump’s statements, prompting the Trump camp to accuse ABC of bias.

Harris has challenged Trump to another debate, but Trump has refused.

At the outset, Brennan vowed to hold a “thoughtful and civil debate,” and it lived up to that goal. Both candidates trained their fire at the top of the ticket, leaving room for civility between the two vice presidential contenders.

During a discussion of guns, Walz said that his 17-year-old son had witnessed a shooting at a community center. Vance said he didn’t know that. “I’m sorry about that,” Vance said.

“I appreciate it,” Walz said.

Vance and Walz sparred on abortion, climate change, and the conflagration in Israel.

Vance introduced himself as the product of a working class family.

“My mother required food assistance for periods of her life, he said. “My grandmother required Social Security to help raise me, and she raised me in part because my mother struggled with addiction for a big chunk of my early life.”

The moderators also challenged Walz and Vance on some of their own past statements. Walz was asked about his claim that he had been in China during the Tiananmen Square crackdown, though he did not get there until later. Walz said that he sometimes would “get caught up in the rhetoric,” and acknowledged that he misspoke.

“I’m a knucklehead at times,” he said.

Vance was asked about his previous statements critical of Trump.

“I’ve disagreed with the President, but I’ve also been extremely open about the fact that I was wrong about Donald Trump,” Vance said, saying that he believed false media accounts about Trump.

On foreign policy, Walz said that Trump is “fickle” and criticized him for minimizing the injuries of American soldiers who were targeted by an Iranian missile strike during his administration.

Vance countered that Trump presided over relative calm on the global stage.

“Donald Trump actually delivered stability in the world, and he did it by establishing effective deterrence,” Vance said. “People were afraid of stepping out of line.”