Trump says Bob Woodward's book is a 'scam' as White House struggles with latest crisis
President Donald Trump. (AFP / NICHOLAS KAMM)

US President Donald Trump on Friday slammed veteran investigative journalist Bob Woodward's damning portrayal of the inner workings of his administration as a "scam" based on made-up quotes.

The book, combined with an incendiary unsigned article in The New York Times by a senior member of Trump's administration, has sparked yet another crisis for the White House and provided fuel for critics who argue that Trump is unfit for office.

"The Woodward book is a scam. I don't talk the way I am quoted. If I did I would not have been elected President. These quotes were made up. The author uses every trick in the book to demean and belittle," Trump tweeted.

"I wish the people could see the real facts - and our country is doing GREAT!"

Drawing on hundreds of hours of interviews, the respected White House chronicler describes a coalition of like-minded aides plotting to prevent the president from destroying the world trade system, undermining national security and sparking wars.

Woodward's is not the first unflattering investigation into Trump's White House, but has been particularly resonant coming from the man who together with Carl Bernstein authored the Watergate expose that brought down Richard Nixon.

Since Watergate, Woodward has been one of the most respected living US journalists, and an authority on modern US presidents who drew praise from Trump himself in 2013 for his work on Obama.

While the journalist does not name his sources, he says he spoke with many people currently or formerly working for Trump, discussing not just the president's personality but also major policy debates regarding North Korea and Afghanistan.

Woodward describes Trump regularly insulting key members of his own team, who are in turn contemptuous of the president.

The president is alleged to have described Attorney General Jeff Sessions -- who angered him by recusing himself from oversight of the Mueller probe into Russian collusion in the 2016 presidential election -- as "mentally retarded" and a "dumb Southerner."

The president is quoted as likening former chief of staff Reince Priebus to "a little rat," and telling his 80-year-old secretary of commerce, Wilbur Ross, "I don't trust you... You're past your prime."

- 25th Amendment -

The book also depicts Trump aides working to head off potential foreign policy disasters, taking more measured steps after the president suggested assassinating his Syrian counterpart and stealing an order that would have cancelled the US-South Korea trade agreement.

Revelations from the book were supported by the unsigned article in The New York Times published Wednesday, which said that "unsung heroes" were quietly working within the administration to frustrate the president's "worst inclinations."

A "whodunnit?" style guessing game has raged in the corridors of power and on social media over the identity of the author, prompting nearly every cabinet-ranked member of the government to deny involvement.

The writer of the article said cabinet members initially considered invoking the 25th Amendment of the US Constitution, which provides for the president's removal if he is "unable to discharge the powers and duties of his office."

They decided against the move, fearing a constitutional crisis, but Democratic Senator Elizabeth Warren took to the airwaves on Thursday to revive the idea.

"If senior administration officials think the president of the United States is not able to do his job, then they should invoke the 25th Amendment," Warren told CNN.

Since the Watergate expose appeared in The Washington Post in the early 1970s, Woodward has published powerful, insightful and often embarrassing books on eight US leaders, including George W. Bush and Barack Obama, based on extensive access to numerous administration insiders.