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.

Donald Trump signs revised travel ban

"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."

In pictures: Protests, pomp and Donald Trump Show all 30 1 /30 In pictures: Protests, pomp and Donald Trump In pictures: Protests, pomp and Donald Trump President-elect Donald Trump acknowledges guests as he arrives on the platform at the US Capitol in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Donald Trump is sworn in as the 45th president of the United States by Chief Justice John Roberts as Melania Trump looks on during the 58th Presidential Inauguration at the U.S. Capitol in Washington AP In pictures: Protests, pomp and Donald Trump President Donald Trump shakes hands with Justice John Roberts after taking the oath at inauguration ceremonies swearing in Trump as the 45th president of the United States Reuters In pictures: Protests, pomp and Donald Trump President Donald Trump raises his fists after his inauguration on the West Front of the U.S. Capitol Getty In pictures: Protests, pomp and Donald Trump U.S. President-elect Donald Trump greets outgoing President Barack Obama before Trump is inaugurated during ceremonies on the Capitol in Washington Reuters In pictures: Protests, pomp and Donald Trump resident-elect Donald Trump arrives on the platform of the US Capitol in Washington DC Getty Images In pictures: Protests, pomp and Donald Trump Attendees partake in the inauguration ceremonies to swear in Donald Trump as the 45th president of the United States at the U.S. Capitol in Washington DC Reuters In pictures: Protests, pomp and Donald Trump US President Donald Trump delivers his inaugural address during ceremonies at the US Capitol in Washington DC Getty In pictures: Protests, pomp and Donald Trump U.S. President Donald Trump waves with wife Melania during the Inaugural Parade in Washington DC Reuters In pictures: Protests, pomp and Donald Trump Protesters registered their rage against the new president Friday in a chaotic confrontation with police who used pepper spray and stun grenades in a melee just blocks from Donald Trump's inaugural parade route. 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Bush and First Lady Laura Bush arrive for the Presidential Inauguration at the US Capitol Rex In pictures: Protests, pomp and Donald Trump Michelle Obama and Dr. Jill Biden share an umbrella as President Donald Trump delivers his inaugural address at the inauguration in Washington DC Rex In pictures: Protests, pomp and Donald Trump Former Democratic presidential nominee Hillary Clinton and former President Bill Clinton arrive on the West Front of the U.S. Capitol in Washington Reuters In pictures: Protests, pomp and Donald Trump U.S. Vice President Mike Pence takes the oath of office on the West Front of the U.S. Capitol in Washington, DC Getty Images In pictures: Protests, pomp and Donald Trump Advisors to President-elect Donald Trump, Kellyanne Conway and Steve Bannon depart from services at St. John's Church during the Presidential Inauguration in Washington Reuters In pictures: Protests, pomp and Donald Trump Protesters demonstrating against U.S. President Donald Trump take cover as they are hit by pepper spray by police on the sidelines of the inauguration in Washington DC Reuters In pictures: Protests, pomp and Donald Trump An activist demonstrating against U.S. President Donald Trump is helped after being hit by pepper spray on the sidelines of the inauguration in Washington DC Reuters In pictures: Protests, pomp and Donald Trump A police officer tries to tackle a protester demonstrating against U.S. President Donald Trump Reuters/Adrees Latif In pictures: Protests, pomp and Donald Trump Police arrest and detain a protester in the street in Washington DC Rex In pictures: Protests, pomp and Donald Trump A police officer falls to the ground as another shoots pepper spray at protesters demonstrating against U.S. President Donald Trump on the sidelines of the inauguration in Washington DC Reuters

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.