Democrats in the United States have raised concerns about interference in the investigation of Special Counsel Robert Mueller after the firing of Attorney General Jeff Sessions Wednesday.

The forced resignation of one of Donald Trump’s earliest supporters because of the President’s unhappiness that he recused himself from overseeing the Mueller probe has set off alarm bells that the country may be heading for a constitutional crisis.

President Trump swiftly appointed Matthew Whitaker the new acting AG, a man who served as Sessions’ Chief of Staff and who has been a long-time critic of the scope of the Mueller investigation.

It was a sudden farewell for Trump’s former Attorney General, the very first Republican Senator at the time to break ranks with his colleagues and go in with a candidate not many initially took seriously.

But the President’s unhappiness with Sessions has boiled over in public after his refusal from overseeing the Mueller probe in March last year due to his close affiliation with the Trump campaign.

Jessica Levinson is a political commentator and a Professor at Loyola Law School in Los Angeles.

“Well, I think he’s signalling things that he has said very explicitly without sending any signals whatsoever, which is he does not like Jeff Sessions. He really does not like Jeff Sessions. He thinks he’s a traitor.”

“He does not think he is a good attorney general and he was literally waiting for the moment that the midterms were over to be able to fire him. I think he’s also signalling the fact that he wants somebody whose thinking is more in line with his to be in charge of the Mueller investigation.”

“And so what he wants is somebody who’s using words about the Mueller investigation like ‘fishing expedition,’ like ‘disgrace’. And I think that’s what we will largely get.”

Trump tweeted as he does when he fires members of his administration that Sessions would be replaced by Matthew Whitaker, who wrote in a 2017 op-ed that the Mueller probe into Russian interference and possible collusion should be limited; warning that without clear boundaries, it could resemble a witch hunt. This is terminology the President himself often uses to describe the investigation.

“My guess is that Robert Mueller has already shared some information to the extent possible with state attorney generals, with other federal prosecutors, because he very rightfully has worried that any day could be, frankly, the last day of the investigation.”

“And so I also think what we have with Whitaker is someone who has said there are places you cannot go in this investigation. And so I think Mueller is acutely aware of the fact that there will be somebody overseeing this who is worried about the timing and the scope.”

Deputy Attorney General Rod Rosenstein, who didn’t comment to reporters when he left his home early Thursday, had been overseeing the investigation to date.

Professor Levinson explains that it’s likely that he’ll be pushed aside by his new boss.

“It’s not clear right now what this means for Rosenstein except that I do think Whitaker is taking over and, therefore, he would be quote unquote, ‘off’ overseeing the Mueller investigation.”

“My guess is he was never terrifically jazzed to be in charge of the Mueller investigation to begin with. But I think that he will likely be reassigned to something else.”

Democrats, who swept to a majority in the House of Representatives this week, have raised their concerns.

“Protecting Mueller and his investigation is paramount. It would create a constitutional crisis if this were a prelude to ending or greatly limiting the Mueller investigation. And I hope President Trump and those he listened to will refrain from that. I find the timing very suspect, number 1., But number 2 our paramount view is that any Attorney General, whether this or another one, should not be able to interfere in the Mueller investigation in any way.”

With their newfound oversight authority in the House, Democrats are expected to convene hearings and call witnesses when they take over in January in their quest to investigate the President’s actions and hold him to account.