The "sheer level of paranoia" coming from President Donald Trump's White House is "untenable to the workings of a republic," former CBS News anchor Dan Rather has said.
Describing the administration as "in freefall" in a Facebook post, Mr Rather asked whether Mr Trump actually believed the claims he has made.
"Even the most grounded of presidents must fight to keep themselves moored to the real world. The Oval Office can be a bubble. Power attracts sycophants and cynics. But I have never seen anything like this," he wrote.
"The sheer level of paranoia that is radiating out of the White House is untenable to the workings of a republic.
"I have a real question if President Trump actually believes what he is saying. Even Richard Nixon, the most paranoid president to date, ruled for years with a relatively calm hand."
The former CBS Evening News anchor added: "This Administration has been an off kilter whirlwind since the inauguration, and news reports suggest that seething anger from Mr. Trump is only getting worse.
"There is a growing consensus that the President may be 'unhinged.' It's a serious allegation, but even if it is not the case, Mr Trump only has himself to blame."
Mr Rather called for people to challenge the President on his unsubstantiated claims former President Barack Obama wiretapped his phone.
"The man who sends out a twitter tirade accusing a former President of crimes for which he provides no evidence, the man who doubles down when everyone with any sense pushes back, that man is our Commander in Chief.
"Every one who normalises Mr Trump now, or has in the past, will have to answer to future generations for their acquiescence, silence or sophistry — if, indeed, not outright cowardice."
He added: "Conspiracy theories are corrosive in society at large. When they dictate national policy, they can be lethal."
Mr Rather concluded: "As the questions mount around Russia, as the circles of defence begin to falter, the determination to create diversions will escalate.
"But if the President hoped he could create a distraction, I think he misjudged the will of the American people. We have woken. We are paying attention. And we love our country too much to let it falter without a fight."
