Senior figures in Donald Trump's administration have privately said the president is "unhinged", an "idiot" and has the understanding of a "fifth-grader", according to an explosive new book.

One top aide is quoted expressing fears that Trump could appear to be a "goddamn dumbbell" while another reportedly said that the president had gone "off the rails".Leading figures are also described removing a letter from Trump's desk so he could not enact a policy change and disregarding a proposal to assassinate Bashar al-Assad, the Syrian dictator.

The claims are made in a new book by Bob Woodward, the reporter made famous for helping uncover the Watergate scandal that brought down Richard Nixon as US president.Highlights from Woodward's book, titled Fear, have been released by the Washington Post, the US newspaper where he is an associate editor.

LISTEN ABOVE AS RICHARD ARNOLD TALKS ABOUT THE SITUATION AND BOOK