Author Michael Wolff said that US President Donald Trump "might be cracking up" following the impact made by his recent book.
Already a best-seller, 'Fire And Fury: Inside The Trump White House' paints Mr Trump as a leader who does not understand the weight of his office and whose competence is questioned by aides.
The President and other White House aides have blasted it as inaccurate trash.
Speaking to Sean O' Rourke on RTÉ Radio 1 this morning, he said that recent attempts by Trump to forge greater international and domestic co-operation was a desperate attempt to appear "stable".
"That more specifically suggests that he is completely freaked out by this book," he said.
"All of this is in response to the book, all [of it] is trying to prove that he is a stable person, a sane person, rather than out of control, outlandish person.
"It has clearly in profound ways gotten under this man's skin. Rather than, to my mind proving that he's a stable genius, it rather looks like he might be cracking up."
He added: "I think Donald Trump sees this book as a mortal threat to his presidency."
He said that Although he described former chief strategist Steve Bannon as "a helpful person in the White House", it was, in fact, the President himself who granted him significant access.
"I've known Trump for a good long time, and when I approached him about doing this, this was funny, because I said I'd like to come down and like to sort of be an observer in the White House and he thought I was asking for a job," he said.
"And I said: 'No, I'm not asking for a job, I want to write a book', and when I said the word 'book' he seemed to completely lose interest.
"And then I said: 'But no, really, I would really like to do this, and I think it's really important for the historic record'.
"And he kind of shrugged and as though to say 'knock yourself out'.
"But I took that as a kind of approval, and it seemed to be. He certainly didn't object when I showed up at the White House and started making appointments with the senior staff."
When asked if he misrepresented Bannon when attributing the word "treasonous" to him when describing the meeting in Trump Tower between Donald Trump Jnr and Paul Manafort, Wolff quickly insisted: "Absolutely, completely, without question, not.
"I'm fond of Steve and I respect his insights, depend on them in many instances, and I know that this has put him in a difficult position.
"When he tried to walk back this, he certainly didn't deny anything that he told me, he tried to say that it was Paul Manafort who he meant to call treasonous, other than Donald Trump Jnr, although he didn't point out that he also said that Donald Trump Jnr would be cracked like an egg on national TV and that he called Donald Trump Jnr afraid of [being called] after the dumb son in the Godfather.
"No, absolutely, categorically, he meant Don Jnr was the potentially treasonous boob."
Trump's former campaign CEO recently stepped down as executive chairman of the conservative news site, but Wolff speculated that Bannon's recent apparent downfall may be part of a wider strategy.
"I assume Steve knew what he was doing here," he said.
"I also believe that Steve had come to see the president as a faulty vessel. At the beginning of the presidency, Steve said the president was his vessel. I think his vessel was no longer carrying water, I think, pretty clearly, Steve had come to think of the President as an idiot.
"I think this book was part of his plan to break with the President. Remember, he told me also that he plans to run for President in 2020."
Wolff painted a picture of an administration in a state of almost perpetual chaos, barely held together under the leadership of Chief of Staff John Kelly.
"One of the terrifying thing about this administration is that nobody knows how bad it could be because nobody can predict what Donald Trump is going to do at any given time, or at any given point during the day," he said.
"It's a black hole. Everybody wanders around trying their best to put one foot in front of the other and full of enormous personal trepidation and trepidation for the country and the world."
He added: "I think John Kelly is a good man and a man who is duty bound and honour bound to try to keep this White House under some control - but I think he has no illusions about what he is up against."
When asked by Sean O'Rourke who President could really trust, Wolff volunteered a single name - young communications director Hope Hicks.
Responding to media criticism of the book, some of which has labelled it as gossip, he said.
"I think it has also gotten under the skin of the Washington press corps. I'm not part of the Washington press corps, I don't do what they do, I don't hang out with them."
When asked if Trump was getting anything right, Wolff volunteered: "I guess the one thing you could say he is getting right is that the chaos prevents him from doing anything much," he said.
"In the great scheme of things, he has probably done much less wrong that we might have thought that he would do because he can't get out of his own way.
"And to be perfectly honest, he's not that interested in doing very much."
Wolf insisted that although he is pleasantly surprised by the impact the book has had, he does not see himself as having any political role.
"My job is not a political job," he said.
"I'm a writer. All I can do is go into a situation and report what I saw and what I heard, and if I can bring that to life, then I've done my job.
"I can't get rid of the President for people. That's somebody else's job."