History is written by the victors but Donald Trump being Donald Trump, he was never going to go quietly. So when the Washington Post reporters Carol Leonnig and Philip Rucker requested an interview about the final year of his presidency, Trump invited them to the palatial Florida estate he used to call his “winter White House”.

The conversation took place not in his private office at Mar-a-Lago but in its gaudy lobby as waiters assembled a buffet dinner including jumbo Gulf shrimp, oysters over ice and bananas foster. A model of Air Force One, painted in Trump’s unrealised redesign, perched on a coffee table. Club members – a Fox News host and Donald Trump Jr’s girlfriend among them – stopped to chat on their way to dinner.

“Trump seemed to love the idea that he was being interviewed as theatre,” Rucker recalls by phone. “He could show off to his club members that these fancy reporters from Washington had flown down just to hear what he had to say. And he enjoyed the interview. He talked to us for two and a half hours and then he invited us at the end to stick around for dinner and sent us to a table in the corner of the patio.”

The upshot of this encounter in March, and private interviews with more than 140 sources, is I Alone Can Fix It, a follow-up to Pulitzer prize-winning Leonnig and Rucker’s bestseller A Very Stable Genius (both titles are direct Trump quotations loaded with irony). It is among a wave of books about Trump’s disastrous final year hitting shelves just six months after he left office.

I Alone Can Fix It portrays a man who put himself before his country. It is packed with hair-raising revelations about the 45th president’s mishandling of everything from the coronavirus pandemic (he has no regrets) to racial justice protests (his only regret is not unleashing the active-duty military), but it made the most headlines with its account of America’s flirtation with fascism.

The key figure here was Gen Mark Milley who, as chairman of the joint chiefs of staff, had the monumentally important job of keeping the military out of politics. His disquiet took root when he joined Trump on a walk through Lafayette Square for a photo op at a historic church soon after the square had been violently cleared of protesters. He apologised, earning Trump’s wrath.

Leonnig recounts: “Gen Milley had no idea when he walked out of the gates of the White House in his camouflage fatigues that he was joining in this fairly bizarre public relations staging and he went to sleep that night making a pledge to himself and to some of his closest confidants and mentors that he was not going to let the military be used and played in that way again for a political purpose.”

She adds: “As the months went on, he became increasingly concerned that Trump would also use the military to create chaos, to create fear as a distraction, to keep his grasp on power – that fear there might be a coup. He vowed he would block that and he spent, according to our reporting, hours and hours monitoring the situation at the White House and among fringe groups, trying to be sure that Donald Trump would not get that chance to get what he called ‘the guys with the guns’.”

Milley’s concerns only grew when Trump refused to concede defeat to Joe Biden in the weeks after the November election. He became so worried that the president might try to deploy the military to remain in power that he and other top officials discussed ways to stop him, including mass resignations.

Trump has responded that he is “not into coups” and “never threatened, or spoke about, to anyone, a coup of our government”, only to add that “if I was going to do a coup, one of the last people I would want to do it with is” Milley.

Milley even compared Trump’s rhetoric to Adolf Hitler’s during his rise to power in Germany, according to the book. “This is a Reichstag moment,” he told aides, referring to the 1933 fire at the German parliament which the Nazis used as a pretext to consolidate power. “The gospel of the Führer.”

‘It’s unbelievable’

The inevitability of online discussions reaching for a Nazi analogy the longer they go on is known as “Godwin’s law”. Journalists are usually discouraged from making such comparisons. And yet here was America’s highest-ranking military officer doing just that.

Rucker reflects: “It would have been unfathomable for an American president to be likened to Adolf Hitler. Just think about the history of Nazi Germany and the history of the United States and the different paths the two countries have taken and it’s just remarkable to contemplate that now in the 21st century, in the year 2020, an American president would have such authoritarian impulses and rhetoric and behavior that he would draw comparisons to Adolf Hitler. It’s unbelievable.”

Even before 2020, Trump had long been compared to autocrats around the world because of his mass rallies, willingness to promote false propaganda, harsh crackdowns on political protesters, contempt for media freedom, scapegoating of minorities, admiration for other strongmen and penchant for hiring family members and putting his name on buildings.

Leonnig says of interviews with first-hand witnesses: “They were quite concerned his go-to was an authoritarian impulse. One of the most horrific curses the president could hurl at any cabinet member or adviser was: you’re weak, you’re acting weak, or that’s a weak idea. Being tough and being strong was so important to him.

“What we’ve learned in the course of reporting for this book and the one before is the president really sidles up to and admires some of the most authoritarian leaders in the world: Vladimir Putin, Recep Tayyip Erdoğan. He has an affinity for them.”

She continues: “Many times we would be surprised to learn that he was very worried about how he looked to other international leaders, almost as if he were on a playground and he was worried about what the other boys thought about him.”

When Trump learned, for example, that his health secretary, Alex Azar, had bought millions of coronavirus vaccine doses from AstraZeneca, he was furious it was a British and not American company because Boris Johnson would laugh at him. Leonnig adds: “Trump’s aides were flabbergasted: why is he worried what Boris Johnson thinks about him buying a lot of vaccine to protect his countrymen?”

Just days after Milley’s “Reichstag moment” warning, Trump addressed supporters at a rally in Washington and exhorted them to “fight like hell”. He then returned to the White House and watched on TV as they laid siege to the Capitol, breaching police barricades, smashing windows and disrupting certification of Biden’s electoral college win.

Rucker recounts: “For a while there he liked what he was seeing. People who were familiar with how he reacted to the television images said he was happy, that he thought it was a beautiful thing to see so many of his supporters acting with such strength, waving his flags, wearing his hats, marching on the Capitol in his name. It was a beautiful sight for Trump.

“When things got really very violent and deadly he, according to our sources, realised that this was a problem and yet he didn’t actually act and do anything. He was effectively awol. He had abdicated his responsibility as commander-in-chief in that moment. And so when it came to organising a federal response – law enforcement and military and national guard – to try to regain control of the Capitol and to bail out those outnumbered Capitol police officers, it wasn’t Trump who did any of that coordination.”

Instead it was left to Vice-President Mike Pence, held in a secure location underground, who worked the phone with leaders at the Pentagon and other senior officials in the government to coordinate the response and save the Capitol.

“Trump, according to our reporting, had no such communication with the Pentagon,” Rucker says. “He had no communication with the vice-president. He just sat there watching television.”

Trump’s daughter Ivanka was at the White House and growing concerned. Mark Meadows, the chief of staff, urged her to pressure the president to publicly back law enforcement and tell his supporters to go home. But she was neither forceful nor effective.

Leonnig says: “Lives were in the balance and it was taking hours for the president of the United States to say anything. Some people likened Ivanka to a stable pony with a racehorse: she’s being brought in to calm her father and get him trotting at the right pace.”

‘For some sick reason I enjoyed it’

No one, it seems, can halt Trump’s blind gallop. Even after the horror of that day – five dead, more than a hundred injured, members of Congress fleeing for their lives – he told Leonnig and Rucker in their interview: “There was a lot of love. I’ve heard that from everybody. Many, many people have told me that was a loving crowd.”

Trump was equally convinced that he won the 2020 presidential election, even though his attorney general, state election officials and numerous judges threw out his bogus claims of voter fraud. It has become known as “the big lie”. So, is he knowingly lying or does he genuinely believe this stuff?

Leonnig comments: “Phil and I spoke to so many people inside the administration who literally were at his shoulder day in, day out, and they told us they are not sure what he believes. They had his ear, they still are not completely persuaded that he believes this, although I must say that when Phil and I were with him in Mar-a-Lago, I was strangely impressed by how completely the former president said all of these things about the election being rigged with a completely committed and straight face.

“Many of the things that are absolutely without any basis in fact – were looked into, run to ground and rejected by his attorney general – he still says are true. And his commitment to those lies physically is as if a person really believes it.”

This was the alternative reality bubble that the authors found at Mar-a-Lago, where up is down, two plus two equals five and a twice-impeached one-term president milks regular standing ovations. Leonnig and Rucker recall that after the interview and dinner, Trump offered to invite them back if they had any follow-up questions and admitted: “I enjoyed it actually. For some sick reason I enjoyed it.”

A vanishingly rare glimpse of self-awareness from the man who loves to hate the press?

Leonnig muses: “I think he recognised that, despite us being part of what he dubs the fake news media, he needs us and enjoys talking about himself.”

• I Alone Can Fix It is published in the US by Penguin and in the UK by Bloomsbury. To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply