Seven million votes more was almost not enough. Had 45,000 gone the other way in Arizona, Georgia and Wisconsin, Donald Trump would still be president. Calls to defund the police nearly cost Joe Biden victory and led to a more than a dozen-seat loss for House Democrats.

Biden had “separated himself from the orthodoxies of his party’s base” but “had no coattails” to spare, Jonathan Allen and Amie Parnes write. As always, culture counts – even amid a pandemic.

But “Unwoke Joe”, as the authors call him, was the one Democrat whose empathy and instincts matched the demands of the times. Lucky is an apt title for Allen and Parnes’s third book.

“In 2016, Trump had needed everything to go wrong for Hillary Clinton to win,” they write. “This time, Biden caught every imaginable break.”

Their joint take on Biden is a prism and scorecard that gives added understanding to the seemingly never-ending war of 2020. Allen is a veteran political writer at NBC News digital, Parnes reports for the Hill. They deliver.

Subtitled How Joe Biden Barely Won the Presidency, Lucky is the first full-length campaign postmortem. It makes the silent parts of the conversation audible and reminds the reader the past is always with us.

The authors convey the cultural dimensions of Biden’s win. He was an old-time north-eastern pol who repeatedly bore witness to personal tragedy. So long in the Senate, he prided himself on his capacity to compromise and reach across the aisle, a trait that Allen and Parnes report elicited scorn from Elizabeth Warren.

Biden also sought to maintain a “close relationship with the police and the civil rights community”, in his own words. It was no accident South Carolina emerged as Biden’s firewall in the primary, or that James Clyburn, a 15-term congressman and the most senior Black member of the House, was pivotal in digging Biden out of a deep hole.

In the election’s aftermath, Clyburn attributed Democratic underperformance to the move to defund the police and the mantras of the left.

“I’ve always said that these headlines can kill a political effort,” he told NBC. For good measure, Clyburn added: “Sometimes I have real problems trying to figure out what progressive means.”

On the other hand, Hillary Clinton and Barack Obama come across as out of sync. We are told that Clinton, the “vampire in the bullpen”, harbored thoughts of another run – until late 2019.

The fact Clinton lost in 2008 and 2016 had not totally dulled her capacity to believe she could unify party and country. Lucky captures Biden in 2016, calling the former secretary of state a “horrible candidate” who failed to communicate what she actually stood for.

Unlike Clinton, Biden understood that simply drawing a contrast with Trump would not be sufficient. Yet Clinton did see that the 2020 Democratic nominee, whoever it was, would be in a fight for “the very soul of the nation”. Charlottesville provided that epiphany to Biden.

Obama too does not fare too well, a fair-weather friend to his vice-president on several occasions, overly concerned with protecting his own legacy. He got some very important stuff wrong. Biden was more attractive and viable than the 44th president and his coterie thought.

In the authors’ telling, Obama was temporarily enamored with Beto O’Rourke. Like Kamala Harris, the former Texas congressman’s candidacy was over before the first primary. For both, stardom did not translate into staying power.

Then, at an event with Black corporate leaders in the fall of 2019, Obama amplified Warren’s chances and trash-talked Pete Buttigieg, then mayor of South Bend, Indiana. Obama reportedly said: “He’s the mayor of a small town. He’s gay, and he’s short.” Unlike Buttigieg, Warren never won a primary. She also finished third in Massachusetts – her own state.

As for Biden, one source describes Obama’s support as “tepid at best”. Obama tacitly backed Biden just days before Super Tuesday in March. Months later, he took his time congratulating Biden on his election win.

Biden’s so-called “brother” failed to call him “on election day, or the next day, or the next, or the next”, according to Allen and Parnes. Obama waited until Saturday 7 November, “the day the networks had finally called the election”. The audacity of caution.

Synchronously, the authors find room for the Biden campaign to unload on Andrew Cuomo and his capacity for fluffing his own ego. The New York governor’s five-minute convention speech devoted only its last eight seconds to the nominee.

“They put his speech on our doorstep, lit it on fire, rang the door-bell and then ran away,” a campaign insider says. To think, in December the press reported Cuomo to be a contender for attorney general.

Lucky is nothing if not clear-eyed. Trump roiled the nation’s waters but failed to bring a decisive shift to its politics. He energized and polarized the electorate along lines of class and education.

College-educated white suburbanites grew more Democratic while the Republicans, once the party of the John Cheever’s country club set, had become home to white voters without four-year degrees. In other words, 3 November delivered an outcome – not resolution.

At Trump’s instigation, our semi-civil civil war turned hot and bloody. It wasn’t antifa but a weaponized segment of Trump’s base that stormed the US Capitol. The 6 January insurrection claimed lives, ruined others and brought the Confederate flag into the halls of Congress: a chilling first.

Democracy and process prevailed. The constitutional architecture “held firm”. But for how long?

As Allen and Parnes observe: “Luck, it has been said, is the residue of design. It was for Joe Biden, and for the republic.”

• Lucky is published in the US by Random House