Former White House lawyer Ty Cobb on Monday said he doesn’t buy President Donald Trump’s claim that the ongoing special counsel investigation is a “witch hunt.”

Special counsel Robert Mueller’s ongoing probe is investigating, among other things, whether the Trump campaign colluded with Russia to help its candidate win the 2016 presidential election.

Trump and his allies have repeatedly called the investigation a “witch hunt” and denied that there was collusion. The president has on a number of occasions floated the idea of firing Mueller.

Cobb, who stepped down from his post as White House lawyer in May, told host Gloria Borger at CNN’s CITIZEN Conference in New York on Monday that he rejects the president’s analysis of the probe. He also praised Mueller, who he said he has “respected” for decades.

“Bob Mueller is an American hero in my view,” Cobb said during a panel with Jack Quinn, who served as White House lawyer under former President Bill Clinton. “He was a very serious prosecutor. He and I first met in the mid-’80s when we were prosecuting different places, and I have respected him throughout.”

During his tenure at the White House, Cobb was the lead attorney dealing with requests from the special counsel. He repeatedly said Trump would eventually agree to meet with Mueller, though the president hasn’t always appeared willing to do so.

Trump replaced Cobb with Emmet Flood, who represented President Clinton during his impeachment hearings.

Sen. Lindsey Graham (R-S.C.), one of Trump’s staunchest allies in the Senate, has also rejected labeling the Mueller probe a “witch hunt.”

“I do believe that Mr. Mueller will be fair; I don’t believe this is a witch hunt,” Graham told reporters in August.

Graham added that Mueller “should be able to do his job” without interference.