The former Counsel to President Richard Nixon during the Watergate scandal said Americans view Donald Trump as “insane”, “angry” and he thinks that Mr Trump’s Presidency is an “unfolding disaster”.

“As I see it, about maybe half the population right now isn’t sure whether he is insane or if he’s just a totally angry man, they don’t know what he’s doing,” John Dean told Sky News.

“About 40 per cent seem to be happy with him and approve of his job and another maybe 10 per cent are pretty confused or don’t care, so it’s very strange over here now.

"We’ve never had a President like this and that’s why I have nightmares.”

Mr Dean, who served under Mr Nixon in the early 1970s and was described by the FBI as a “master manipulator”, speculated that the current President appeared to have an “attention deficit disorder” and had not made any effort to become more Presidential.

“I see it as unfolding disaster at this point,” he said.

“I’m kind of happy every morning when I wake up to see he hasn’t blown up some part of the world.”

Several decades ago, Mr Dean pleaded guilty to a single felony in exchange for being the key witness in the prosecution of the Nixon administration.

In the current administration, former national security adviser Michael Flynn has requested immunity from prosecution in exchange for testifying in front of the Senate and House intelligence committees about alleged ties between Trump aides and Russia. The request has been described as “not on the table”.

The remarks from Mr Dean, now an author, lecturer and columnist, follow similar concerns from Richard Painter, former Chief Ethics Counsel to George W Bush, and Norman Eisen, former Chief Ethics Counsel to Barack Obama.

The latter two are part of a group of plaintiffs suing the President for alleged conflicts of interest at home and abroad while in the White House.

Mr Trump’s approval rating dropped to a record low of 35 per cent on 28 March, according to a Gallup poll, the lowest point so early on in a President’s first term in decades.