WASHINGTON – Newt Gingrich stepped up his fierce defense of Donald Trump on Sunday by suggesting that former FBI Director James Comey may be part of a federal probe – not the president.

“Comey may be under investigation,” the former House speaker floated on ABC’s “This Week.” “If you have an obstruction case, Comey has got to be one of the major witnesses.”

Gingrich said there’s “no evidence” the president ever impeded any Russia investigation and Trump fired the FBI director because “Comey’s public behavior was so destructive.”

Comey helped prompt the appointment of a special counsel that’s become a legal “nightmare” that’s “trying to block the Trump presidency.'”

Trump is understandably ticked, he said.

“I think he’s furious,” Gingrich said. “I think Trump sits there and says, ‘let me get this straight, I know I didn’t do anything with the Russians. Comey has said three times I didn’t do anything with the Russians. Nobody on Capitol Hill has any proof I did anything with the Russians. And now I get an independent counsel who is going to mess up at least the next year, at a minimum, and who, by the way, you’ll notice is expanding his charge.”

Gingrich once praised Special Counsel Robert Mueller on May 17 as a “superb choice” and praised his reputation as “impeccable for honesty and integrity.”

On May 19, Trump nominated Gingrich’s wife, Callista, to be part of his administration as ambassador to the Vatican.

Gingrich then flipped his view about Mueller and has publicly questioned his credibility and fairness and joined Trump by calling the investigation a “witch hunt.”

Gingrich blamed his flip-flop on Comey’s testimony to Congress that he leaked a memo about his private conversation with Trump in effort to spark the appointment of a special counsel.

“I, frankly, began to switch the minute Comey, in his remarkable public statement, says, I deliberately leaked to a college professor to leak to The New York Times for the purpose of getting a special counsel,” Gingrich said. “OK, now the special counsel happens to be a close friend of Comey, which is weird.”

But Rep. Adam Schiff (D-Calif.) blamed Gingrich’s about-face on opportunistic politics.

“The only thing that really has changed is the president is attacking Bob Mueller and therefore Newt Gingrich is attacking Bob Mueller,” said Schiff, a member of a House committee investigating Russian meddling in the election.

“What’s happening here is the president wants to take down Bob Mueller,” Schiff added on ABC’s “This Week.” “His lawyer wants to take down Bob Mueller. And the question is why? And I think the answer is they want to lay the foundation to discredit whatever Bob Mueller comes up with. They’re essentially engaging in a scorched earth litigation strategy that is beginning with trying to discredit the prosecutor.”

Trump seemingly admitted he was under investigation for obstruction of justice – though his attorneys deny this – when he tweeted Friday: “I am being investigated for firing the FBI Director…”

Such tweets aren’t helping, Gingrich said.

“Trump has a compulsion to counterattack,” Gingrich said. “And is very pugnacious. I don’t think it serves him well.”

“I don’t think that tweet helped him,” Gingrich said. “But it’s almost like it’s who he has been his whole life. I mean, he’s been a fighter his whole life. He is infuriated, and legitimately, in my judgment, by this whole Russian baloney.”