Trump at National Prayer Breakfast: Pray for 'Celebrity Apprentice'

Like every president since Dwight D. Eisenhower, President Donald Trump attended the annual National Prayer Breakfast. But the 45th president was the only one to ask the bipartisan gathering to pray for Arnold Schwarzenegger.

Trump did address faith in his speech Thursday, but he also took jabs at "Celebrity Apprentice" after the show's producer Mark Burnett introduced him.

"When I ran for president, I had to leave the show. That's when I knew for sure I was doing it," Trump said. "And they hired a big, big movie star, Arnold Schwarzenegger, to take my place. And we know how that turned out. The ratings went right down the tubes, it's been a total disaster, and Mark will never, ever bet against Trump again. And I want to just pray for Arnold if we can for those ratings, OK?"

Muted laughter followed the joke about the NBC show, which helped to vault Trump to nationwide fame.

Trump still has an executive producer credit on the program and gets a per-episode fee likely "in the low five-figures," according to Variety. It marks the second time since his election that Trump has mocked the show's ratings and sparked media coverage of a clash between him and Schwarzenegger.

Schwarzenegger, the former California governor, responded in a video posted to Twitter, asking Trump to switch jobs.

"Hey Donald, I have a great idea. Why don't we switch jobs? You take over TV because you're such an expert in ratings. And I take over your job, and people can finally sleep comfortably again," he said.

@Schwarzenegger: The National Prayer Breakfast?

Later on Thursday, White House spokesman Sean Spicer said Trump's comments were meant as a "lighthearted moment." Spicer also said Mark Burnett, creator of "The Apprentice," was at the breakfast.

"If you look at the totality of his remarks, they were absolutely beautiful. And I think to hone in on that, it was a lighthearted moment he was trying to have with a big supporter of the National Prayer Breakfast and a personal friend," Spicer in a news conference.

The annual National Prayer Breakfast started in 1953.

Disclosure: Like CNBC, NBC is a unit of Comcast.

— CNBC's Elizabeth Gurdus contributed to this report.