CNN may be gearing up for a legal battle over the Trump administration's revocation of chief White House correspondent Jim Acosta's permanent press credentials.

Former ABC News reporter and anchor Sam Donaldson appeared Sunday on CNN's "Reliable Sources" and said he believed a lawsuit had already been filed.

"I hope I'm not mistaken, but it's my understanding that CNN and Acosta have sued, that there will be a court hearing on Tuesday on this very matter that we've been discussing," Donaldson said.

Host Brian Stelter replied that he was not aware of such a case.

A CNN spokesperson told the Washington Examiner that a lawsuit has not been filed yet. "No decisions have been made. We have reached out to the White House and gotten no response," the spokesperson said.

White House press secretary Sarah Sanders announced last week that Acosta's hard pass was suspended until further notice over a heated press conference encounter he had with President Trump during which a White House intern tried to wrestle the microphone from the journalist.

[More: 'There could be others': Trump poised to ban more journalists from White House]

Acosta has denied "placing his hands" on the young woman as some have alleged, and a video tweeted out by Sanders of the incident has garnered controversy related to whether it was doctored to make it look more intense.

Donaldson said he was told about the possible legal action because "I've been asked to give an affidavit, which I prepared, to be submitted to the court."

Donaldson — who, like Acosta, had confrontational interactions with administrations he covered for ABC News during his decades-long career — said he had spoken with the CNN correspondent about the furor.

"I emailed him and said, 'Keep it up, don't worry about the vicious attacks on you by anybody, and the threats and all of this. You're performing in the best appearance of a reporter, you're doing your job properly, and it's a badge of merit,'" Donaldson said.

Also on the show was Floyd Abrams, a constitutional law expert, who said CNN would have a "really strong lawsuit" against the White House.