For years, Biden, who relied on his government salary, was among the least prosperous members of the United States Senate. (In the two years after he left the vice presidency, the Bidens earned more than $15 million, from speeches, teaching, and book deals.)

He has parted with youth grudgingly. His smile has been rejuvenated to such a gleam that it inspired a popular tweet during the 2012 campaign: “Biden’s teeth are so white they’re voting for Romney.” His hairline has been reforested, his forehead appears becalmed, and Biden generally projects the glow of a grandfather just back from the gym, which is often the case.

By the end of August, ten weeks before the election, Biden led Trump by an average of at least 8 percentage points. But no earthly inhabitant expected an ordinary end to the campaign.

The world’s richest, most powerful country botched even rudimentary responses to the pandemic—finding masks, making tests—and some agencies proved to be so antiquated and starved of resources that they used fax machines to share data. The White House offered policies that read like mock Kafka; even as people were advised against dining out, it was proposing a corporate tax break on business meals.

When Larry Hogan, of Maryland, a Republican governor at odds with Trump, ordered test kits from South Korea, Hogan felt the need to deploy his state police and National Guard troops to protect the shipment, for fear that the federal government would try to seize it.

On Fox News in April, Jared Kushner, the president’s son-in-law and one of the leaders of the coronavirus response, declared the administration’s effort “a great success story.” In the four months afterward, at least 110,000 more people died.

According to a senior aide to Bernie Sanders, Biden told Sanders, in a phone call about a possible endorsement, “I want to be the most progressive president since FDR.”

The median American age in 2020 was thirty-eight years. The median U.S. senator was sixty-five. The current Congress was among the oldest in history. Senate Majority Leader Mitch McConnell was seventy-eight; House Speaker Nancy Pelosi was eighty. The difference in age was at the root of a profound difference in worldview. In the words of Patrick Fisher, a Seton Hall professor who specializes in the political dynamics of age, “Demographically, politically, economically, socially and technologically, the generations are more different from each other now than at any time in living memory.”

Between 2013 and 2017, the median age of members of the Democratic Socialists of America dropped from sixty-eight to thirty-three. Many others expressed a desire for a socialism that was closer to the New Deal.

In comments the previous year, Obama bemoaned the emergence of a “circular firing squad” in the party. “This idea of purity, and you’re never compromised, and you’re always politically woke, and all that stuff, you should get over that quickly,” he said.

“I’m paying off Beau Biden’s college loans,” he said, referring to his firstborn son, who died in 2015. “He never missed a payment, but when he graduated from undergraduate school and law school, it was $124,000 he owed.”

Jeff Connaughton, a disenchanted former aide, once called Biden an “egomaniacal autocrat.” But Connaughton, who became a lobbyist, also admired Biden’s contempt for the corrupting glad-handing of Washington. “Biden never lifted a finger for me or for one of my clients,” he wrote, in his book, The Payoff. “Unlike most of Congress, he hardly ever schmoozed with the Permanent Class. He did the best he could to stay as far away from it as possible.”

Biden is the first Democratic nominee without an Ivy League degree since Walter Mondale, in 1984. In a milieu of Rhodes Scholars and former professors, he is thin-skinned about condescension, real and imagined. He was barely in the West Wing before The Onion declared, in a headline, “Shirtless Biden Washes Trans Am in White House Driveway,” establishing a theme—“Amtrak Joe,” the hell-raiser at the end of the bar—that was so enduring that it obscured the fact that he is a lifelong teetotaler.

In Gates’s memoir, Duty, he directed his harshest criticism at Biden. He called him “impossible not to like” but “wrong on nearly every major foreign policy and national security issue over the past four decades.”

The 1999 repeal of the Glass-Steagall Act, which once separated commercial and investment banking, partially facilitated the 2008 financial crisis. (Over the years, Biden has expressed regret about other votes, including his support for the invasion of Iraq and for tougher sentencing on the possession of crack cocaine.)

Biden began the race as the front-runner, but he seemed unfocused and out of step. During a debate, he botched an invitation to text the campaign at “30330” and instead declared, perplexingly, “Go to Joe 30330.” Rather than eliciting donations, it generated a night of Twitter memes, such as “How do you do, fellow kids?” In debates, he rarely fought back and sometimes yielded the floor with the unfortunate phrase “My time is up.”

If he had any hope of staying in the race, it would come down to South Carolina, where Black voters make up roughly 60 percent of the Democratic Primary electorate.

On February 26, Clyburn supplied an emotional endorsement: “I’m fearful for my daughters and their future, and their children, and their children’s future.” With Biden at his side, he said, “We know Joe. But, most importantly, Joe knows us.” Biden won South Carolina by 29 points. With astonishing speed, his rivals dropped out and endorsed him. There were huge surges in turnout (up by nearly 50 percent in Texas and a hundred percent in Virginia), including many college-educated suburban independents and Republicans who had once supported candidates like Mitt Romney. On Super Tuesday, Biden won ten out of fourteen states. Sanders stayed in a while longer, but the race was effectively over.

I asked Klobuchar why she endorsed Biden so fast, and she mentioned specific moments from their dealings over the years—the time he had complimented a speech during her first nervous year in the Senate; the consolation call he paid to one of her friends, after a death in the family. “There are a lot of people that have a lot of love for Joe Biden and know him well,” Klobuchar told me. “We have the mission of beating Donald Trump, and I really believed that, with the power and support that was given to me, what was the best thing I could do with it? Instead of frittering it away for one more debate.” She continued, “I just full-throated endorsed him. Someone said, ‘Oh, did you try to negotiate things?’ And I’m like, ‘Are you kidding? No.’ ”