President Trump ‘certainly believes’ he has power to fire Mueller: White House

The White House says the Department of Justice said Trump can fire Mueller.

“I know a number of individuals in the legal community and including the Department of Justice said he has the power to do so,” Sanders said.

On Monday, Trump mused about firing Mueller before a meeting with military leaders at the White House.

"Why don't I just fire Mueller? Well I think it's a disgrace what's going on. We'll see what happens. But I think it's really a sad situation when you look at what happened. Many people have said you should fire him,” Trump said. “So we'll see what happens. I think it's disgraceful and so do a lot of other people. This is a pure and simple witch hunt.”

The regulations governing the special counsel stipulate that the “special counsel may be disciplined or removed from office only by the personal action of the Attorney General.”

The White House counsel's office did not respond to a request for comment.

“I think the less the president says about this whole thing, the better off he will be. And I think that Mueller is a person of stature and respected and I respect him. Just let the thing go forward,” Grassley said.

Sanders, when pressed about the president’s comments by ABC, simply referred back to Trump.

"I think that the president is clear that he thinks this has gone too far and beyond that, I don't have anything to add," said Sanders.

Tuesday morning, the president sent out angry tweets:

ABC News' Mariam Khan and John Parkinson contributed to this report.