Former New York City Mayor Rudy Giuliani (R) on Sunday denounced a Democratic “pile-on” against New Jersey Gov. Chris Christie (R).

Giuliani accused the New Jersey Democrat leading the investigation into the George Washington Bridge lane closures last year of having prejudged the outcome of the probe. He said New Jersey Assemblyman John Wisniewski wasn't fit for the role.

“You have a Democratic legislature with a guy who'd like to be governor, who very, very oddly announces at the beginning he doesn't believe the governor,” Giuliani told CBS's "Face the Nation." “And no Democrat in the state sees that it's odd that he should be running an investigation when he's already announced that he knows the answer that none of us know the answer to. He knows the answer: The governor is lying. He should not be running that investigation.”

Giuliani went on to say the Republican Governors Association should keep Christie as its chairman unless the allegations he knew of the closures ahead of time are substantiated. The remarks come after Giuliani took flak from Christie allies for saying there was a “50-50 chance” the allegations were true.

“I think the governor knows the consequences,” Giuliani said Sunday. “If he's lying, it's a really bad situation. If he's not lying, then something very unfair is being done to him. So let's see what happens.”

Wisniewski shot back later on the show.

“He's prejudged everything that's been said,” he said of Giuliani. “What I've said is I have skepticism about the governor's statement.

“I haven't said that the governor has responsibility for this. I haven't said that the governor knew when this was happening.”

Wisniewski said it was “premature” to call for Christie's resignation or impeachment.

“We don't have enough facts to even get to that conversation,” he said. “We need to get all the facts on the table. We need to make decisions about who knew what when. And when that's done, maybe it might be appropriate at that time to have that conversation. But clearly we're way ahead of that right now.”

The White House has strived to stay out of the fray after special adviser John Podesta called the revelations that Christie staffers ordered the lane closures as political retribution a “killer” for Christie and his presidential aspirations in 2016.

“I think John was just reacting to a question,” White House chief of staff Denis McDonough told "Face the Nation." “So we've been pretty clear that this is a New Jersey matter to be resolved in New Jersey. We don't have a role in this.”