Republican strategist Alex Castellanos on Sunday warned President Donald Trump to get “good legal help now, because the storm is coming” in Special Counsel Robert Mueller’s Russia probe.

"The president – it’s hard to believe that someone like Donald Trump, who has been a disrupter all his life, who has flouted his way to business success, that Robert Mueller is not going to dig up something in Trump’s complicated financial history to say look, the president of the United States did this and it was wrong. And it’s hard to believe then that when Republicans lose the House in 2018, maybe by 40 or 50 seats, that House is not going to impeach him,” Castellanos said during an appearance on ABC’s “This Week.”

“And it’s also hard to believe that a U.S. Senate that’s going to be scared to death, though may still be in Republican hands, is not going to take a serious look when it has to deal with this president. So get good legal help now, because the storm is coming.”

Trump is cooperating with Mueller’s investigation, but has publicly bristled at the probe, which he has called a “witch hunt” intended to undermine his presidency. The president once reportedly wanted to fire Mueller, but backed off after White House counsel Don McGahn threatened to resign.

Mueller reportedly wants to question Trump about his dismissals of former FBI Director James Comey and former national security adviser Michael Flynn, per CNN.

Trump's lead lawyer, John Dowd, resigned on March 22 after arguing with the president over how to respond to Mueller's prosecutors. Dowd urged a cooperative approach and Trump wanted to sit down with Mueller. Trump is now only represented by Ty Cobb and Jay Sekulow, who have been advising the president in the Russia probe since last summer.