Michael Wolff's tantalising takedown of 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 GOP's defence of this indefensible president appears even more preposterous following Wolff's revelation, in his new book Fire and Fury, of former adviser Stephen 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.)

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 Robert Mueller.