OPINION: Michael Wolff's tantalising takedown of US President Donald Trump's White House is so tightly packed with tales of political convulsion and personal betrayal that official Washington will be buzzing off its sugar high for weeks.

But after the shock of Wolff's account of Trump's willful ignorance and intellectual incoherence fades, Americans will be left with the inescapable conclusion that the president is not capable of fulfilling his duties as commander in chief.

The Republican Party's defence of this indefensible president appears even more preposterous following Wolff's revelation, in his new book Fire and Fury, of former adviser Steve Bannon's observation that members of Trump's team, including his son, committed nothing less than treason. (Disclosure: I am thanked in the book's acknowledgments and make an appearance in a handful of passages.)

MANUEL BALCE CENETA/AP US President Donald Trump says he can read, but plenty of people have questioned his ability to focus on the written word.

Republican politicians who have spent the past year eagerly wading through the slimy political backwash churned up by Trumpism will look even more foolish aping the former reality star's attacks on the special counsel. Despite their desperate declarations that the Vietnam war hero is dragging his feet, Robert Mueller III has proved himself ruthlessly efficient in rooting out public corruption.

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JONATHAN ERNST Morning Joe host Joe Scarborough, left, asked US President Donald Trump, "Can you read?"

In just the past two months, Trump's first national security adviser and most trusted travelling companion pleaded guilty to federal charges; he is now co-operating with Mueller's investigation. Trump's campaign manager through the Republican National Convention was also arrested, charged and released only after posting US$10 million (NZ$14 million) in bail. A man Trump identified as one of his top foreign policy advisers has also pleaded guilty in US federal court and is co-operating with the feds. Another Trump campaign aide was charged in a 12-count indictment. And with the release of Fire and Fury, we now know that yet another campaign official for the Republican president - one who subsequently served in his White House - believes that close Trump advisers were "treasonous" to meet with Russians during the campaign.

A cancer again is growing on the US presidency, and few know whether the 45th president will survive a single term. Bannon has his doubts. "He's not going to make it," Bannon told Breitbart staffers, according to Wolff. "He's lost his stuff."

But if Trump does escape legal prosecution, Wolff's terrifying political tome adds weight to a growing body of evidence that the Manhattan billionaire is temperamentally unfit to serve. An email Wolff describes as "purporting to represent the views" of chief economic adviser Gary Cohn neatly summarises what campaign workers and White House staff have been telling me about Trump for two years. He is an "idiot surrounded by clowns. Trump won't read anything - not one-page memos, not the brief policy papers; nothing. He gets up halfway through meetings with world leaders because he is bored. And his staff is no better."

Fellow Morning Joe presenter Mika Brzezinski and I had a tense meeting with Trump following what I considered to be a bumbling debate performance in September 2015. I asked the then-candidate a blunt question.

"Can you read?"

Awkward silence.

"I'm serious, Donald. Do you read?" I continued. "If someone wrote you a one-page paper on a policy, could you read it?"

Taken aback, Trump quietly responded that he could, while holding up a Bible given to him by his mother. He then joked that he read it all the time.

I am apparently not the only one who has questioned the president's ability to focus on the written word. "Trump didn't read," Wolff writes. "He didn't really even skim. If it was print, it might as well not exist. Some believed that for all practical purposes he was no more than semiliterate. Others concluded that he didn't read because he didn't have to ... He was postliterate - total television."

But Fire and Fury reveals that White House staff and Cabinet members believed Trump's intellectual challenges went well beyond having a limited reading list: US Treasury Secretary Steven Mnuchin called him an "idiot", Cohn dismissed him as "dumb", national security adviser H.R. McMaster considered him a "dope" and US Secretary of State Rex Tillerson infamously concluded that the commander in chief was a "moron".

The US is a nation that spent the past 100 years inventing the modern age, winning World War I, defeating Hitler and winning World War II, and liberating half of Europe by beating the Soviets in the Cold War. But today, it finds itself dangerously adrift at home and disconnected from the allies abroad that made so many of those triumphs possible. The world wonders how the United States will survive Donald Trump. And I ask, what will finally move Republicans to deliver a non-negotiable ultimatum to this unstable president? Will they dare place their country's interests above their own political fears? Or will they only move to end this American tragedy when there is nothing left to lose?

* Joe Scarborough hosts MSNBC's Morning Joe programme, with Mika Brzezinski, in the US

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