A dinner of clams and Arctic char at Michael Wolff’s Greenwich Village home set the stage for a book that – in the author’s own estimation – has become “an international political event”.

Among the guests were former chairman of Fox News Roger Ailes, expelled from the Murdoch empire over claims of sexual harassment and about to retire to Palm Beach, and Steve Bannon, the would-be inheritor of Ailes’ rightwing political media crown who barely six weeks earlier had orchestrated Donald Trump’s improbable election victory.

“It was six months since Roger had been thrown out of Fox so it wasn’t about having a powerful person here, just the opposite,” Wolff told the Guardian from a low-slung chair by the fireplace in his study. Bannon’s invite came next. “I asked him on the spur of the moment: ‘Roger is coming for dinner. Do you want to come?’”

As the storm generated by Wolff’s Fire and Fury has swept over Trump, Bannon and the White House, Wolff has wondered if Ailes vouched for him that night in January 2017, perhaps over the baba au rhum dessert, even as the torch of populist Republicanism was passed from one man to the other.

“I’ve often thought this is a possible thing that happened,” Wolff said.

Either way, it is the creation story of a book that demolished any illusions about Donald Trump’s improbable White House.

The book’s immediate effects have been well-described elsewhere. Among them, the immolation of Bannon’s relationship with Trump and his Breitbart paymasters, and Trump’s bizarre efforts to demonstrate mental competence that, as reported by Wolff, his aides and inner circle routinely and openly called into question.

“Almost all of the stuff that has been focused on seems kind of random to me,” Wolff said. “It’s all explosive because that’s the thing about Donald Trump. He’s so anomalous, so not what he’s supposed to be, that everything he does is at some level preposterous.”

Is the president incapable of carrying out his duties?

“I don’t know if the president is clinically off his rocker. I do know, from what I saw and what I heard from people around him, that Donald Trump is deeply unpredictable, irrational, at times bordering on incoherent, self-obsessed in a disconcerting way, and displays all those kinds of traits that anyone would reasonably say, ‘What’s going on here, is something wrong?’”

This week, Trump called a bipartisan, on-camera discussion on immigration and border security. “This was clearly to establish himself as sane in reaction to the book,” Wolff said. The meeting was strange for several reasons, including Trump’s eagerness to agree with everybody there.

“It fits another premise of the book,” Wolff said. “He doesn’t care. He just wants somebody else to do his work. He wants a win and the nature of the win doesn’t really matter.

“I’ve talked to a number of Donald Trump friends and cronies. He ran on the idea of ‘I’m a negotiator’ but they all say he’s never negotiated anything. Negotiation requires detailed understanding. It’s methodical. He can’t do it.”

The contrived display didn’t last. Trump was soon back to business-as-usual, referring to Haiti, El Salvador and most of Africa as “shithole countries”, setting off a new round of widespread denunciation.

‘This guy is a complete fool’

On the eve of publication, Wolff and his publishers were facing a legal effort by Trump to block publication. It only inspired them to rush the book forward, after the Guardian first reported its contents.

“It’s another example of him being out of control,” Wolff says. “I know that everybody was trying to stop him from doing this. He couldn’t be stopped. His head had exploded, so he did what no president has ever done: attempt to sue someone for defamation and invasion of privacy.

“There are two sides. I was sort of appalled by an attack on the constitutional bulwark on what we do as journalists and how we live as Americans. The other side, is this guy is a complete fool. All he managed to do was call more attention to my book. He just shoots himself in the foot at every opportunity.”

For Wolff, the only change to his life so far has been to keep his wooden shutters closed, to block the sight lines of occasional paparazzi. When he has left his house, he has found himself propositioned for selfies with strangers.

Despite Trump’s denials, Fire and Fury was authorized, albeit in the chaotic Trump modus operandi. After writing relatively positive profiles of Trump and Bannon for the Hollywood Reporter, Wolff joined the parade of job-seekers and ring-kissers at Trump Tower in the weeks after the astonishing election result.

“I said to the president, ‘I’d love to come down and be an observer at the White House.’ That’s when he thought I was asking for a job. I said, ‘No, no. I might want to write a book.’ His face fell. He was completely uninterested. So I pressed a little. I’d really like to do it. So it was, ‘Yah, yah. OK sure.’”

Thus began a Washington adventure for a classic and controversial New York media scribe. Visitor logs record Wolff visiting the White House more than 20 times in the first eight months of the new administration.

“I went in with the inclination to seem like a journalist with purpose but you lose that when literally everyone is ignoring you,” Wolff said. “You really become part of the furniture, this guy who is so pathetic, people really make an effort to entertain you.

“Then they’d say, ‘Who are you waiting for?’ Often that would be Bannon, who’d never ever keep an appointment. So they go, ‘Uh uh yeah, wanna come back?’ Suddenly you’d find yourself in the chief-of-staff’s office.”

Fire and Fury has come under sustained criticism, in particular from the Washington press corps. Last week CNN anchor Jake Tapper told chat show host Seth Meyers it was a book that “abandoned all standards”. He also said there was “poetic justice” that it would define the Trump presidency.

Criticism has largely focused on misspellings and relatively minor fact-checking problems. “The truth is every book has these kinds of mistakes but not every book rises to the level of an international political event,” Wolff said.

Such attacks may mask a larger issue: Wolff has eaten the critics’ lunch, as wolves are prone to do. It seems it has taken the step-back view of an author to show clearly the defining characteristics of the Trump White House.

“They’re stuck in the weeds,” he said of the US press. “I’m clearly not stuck in the weeds. I have obviously managed to convey this story in a way that people get, that moves them and they understand.”

The problem for the Washington press, as for everyone, is that the entirely abnormal Trump presidency has been effectively normalized.

“In the beginning,” Wolff said, “it was, ‘Don’t normalize them.’ But that is effectively what they’ve done. There is an explosive story every day which makes you forget about what happened the day before.

“So suddenly this book comes along, provides a context and everybody – literally everybody – goes, ‘Oh my God, now we understand this.’ The Washington press has left everybody fearful, befuddled, desensitized and suddenly, from their response to this book, people are able to say, ‘Yes I understand this...’

“I got to a truth that no one else had gotten to, not that they didn’t know it. Everyone around Trump thinks he’s a charlatan, a fool, an idiot and someone ultimately not capable of functioning in this job. Pretty much nobody has said that although the Washington reporters are talking to the same people I spoke to and getting the same stories.”

‘This is not a book about my impressions’

Wolff has been accused of obfuscating over how much time he spent with the president. The White House maintains he was never granted an Oval Office interview. Wolff does not claim to have had one.

“Let me say clearly,” he said, “I had approximately three hours of conversation with Donald Trump between June 2016 and now. Some of that took place during the campaign, during the transition and in the White House.”

On page 92 of Fire and Fury, Wolff writes: “On 6 February, Trump made one of his seething, self-pitying and unsolicited calls without any presumption of confidentiality to a passing New York media acquaintance”. The call lasted 26 minutes, Wolff writes, as the president attacked various media bigwigs, disputed reports of Bannon’s influence over him, and said he was not the “kind of guy” to wear a bathrobe.

The call, one can surmise, was to Wolff himself.

“Let me not say to whom the call was made,” he said. Instead, he insisted he never wanted there to be any use of first person in his book, a technique that goes back to the “new journalism” of the 1960s.

Wolff says he is uninterested in politics. What fascinates him is people and power, and the unprecedented scenario that emerged from Trump’s win.

“This has happened, it shouldn’t have happened, no logic would have indicated it would happen. But it’s there so how do you deal with it? This is not a book about my impressions, it’s a book about the impressions of people around him. It was important to me not to make my relationship or my impressions of the president the focus.”

Bannon, Wolff wrote, said Donald Trump Jr’s meeting with Russians in Trump Tower in June 2016 was “treasonous” and predicted he would be “cracked like an egg on national TV” – the words that led to his excommunication.

Bannon, Wolff surmises, was already headed for the exit. But how could he be so reckless as to disrespect the boss’s son? Was he drinking? “No. He was not drunk. I’ve never seen him drunk, though I’ve seen him refuse drinks many times...

“My theory is he thought [the far-right Alabama Senate candidate] Roy Moore was going to win. That would make Bannon kingmaker and Trump the loser. Bannon would have gone into 2018 as the guy with all the leverage. Bannon had come to the conclusion that Trump, in addition to being an idiot, was an impediment to his true populist agenda.”

How does Wolff feel about Bannon now? “I feel a little guilty that I put him in a position he did not intend to be in. But he’s a big boy, and he was well aware of the risks he took when he spoke to me.”

Wolff, who would not say if he had heard from Bannon since his downfall, said he had been “left wondering if he’s the ultimate strategic mind or just a guy who can’t stop himself from talking”.

Wolff will soon set off on a European tour. He appears composed but there have been sleepless nights, including the one after the Guardian obtained a copy of Fire and Fury and Trump duly erupted.

He discounted the idea of another celebrity presidency, saying he did not see Oprah Winfrey running, and said: “I think this will stand as a cautionary tale.”

He also conceded that those could be famous last words.

“Look, forget everything else. This is a fantastic story and these are phenomenal characters. Trump is an amazing character. Bannon is, for me, a gift from the gods. And on top of everything else, [Anthony] Scaramucci! Jared Kushner! It’s too good to believe.

“This experiment happened. Let’s make someone president who is different and in every way the exact opposite of everything we think a president is and should be. That was the experiment.

“The positive here is people have realized the experiment has been a failure – even a great number of people who voted for him.”