NEW YORK – CNN suspended commentator Robert Novak indefinitely after he swore and walked off the set Thursday during a debate with Democratic operative James Carville.

The exchange during CNN’s “Inside Edition” came during a discussion of Florida’s Senate campaign. CNN correspondent Ed Henry noted when it was through that he had been about to ask Novak about his role in the investigation of the leak of a CIA officer’s identity.

A CNN spokeswoman, Edie Emery, called Novak’s behavior “inexcusable and unacceptable.” Novak has apologized to CNN, and CNN apologizes to viewers, she said.

“We’ve asked Mr. Novak to take some time off,” she said.

A telephone message at Novak’s office was not immediately returned Thursday.

Carville and Novak were both trying to speak while they were handicapping the GOP candidacy of Katherine Harris. Novak said the opposition of the Republican establishment in Florida might not be fatal for her.

“Let me just finish, James, please,” Novak continued. “I know you hate to hear me, but you have to.”

Carville, addressing the camera, said: “He’s got to show these right wingers that he’s got a backbone, you know. It’s why the Wall Street Journal editorial page is watching you. Show ’em that you’re tough.”

CNN’s Ed Henry, right, said he told Novak before the show that he would ask about his role in the leak of a CIA agent’s name, but Novak’s tantrum prevented that. “Well, I think that’s bull—- and I hate that,” Novak replied. “Just let it go.”

As moderator Henry stepped in to ask Carville a question, Novak walked off the set.

Only two weeks ago, CNN executives defended their decision to keep Novak on the air during the ongoing probe into the revelation of CIA officer Valerie Plame’s identity. In a July 2003 newspaper column, Novak identified Plame, the wife of administration critic and former U.S. ambassador Joseph Wilson, as a CIA operative.

Wilson has said the leak of his wife’s name was an attempt by the administration to discredit him. Two other reporters connected to the case openly fought the revelation of their sources, and Judith Miller of The New York Times has been jailed for refusing to cooperate with prosecutors.

Novak has repeatedly refused to comment about his role in the federal investigation.

After Novak walked off on Thursday, Henry said that Novak had been told before the segment that he was going to be asked on air about the CIA case.

“I’m hoping that we will be able to ask him about that in the future,” Henry said.

Novak has been a longtime contributor to CNN, taking the conservative point of view during the just-canceled “Crossfire” show.