[MUSIC PLAYING] “Good morning.” “Good morning.” “Good morning.” So this is Joe Biden in January of 2017 during his last few weeks as vice president. “Do we know [INAUDIBLE]” He was surprised with the Presidential Medal of Freedom. “Hey, guys.” And he was headed home to Delaware. “Back on Amtrak.” Fast forward to the present, and it now looks pretty clear that Joe Biden will be the Democratic nominee for president. The path to victory has continued to narrow for Bernie Sanders. So how did we get here? And how did Joe Biden pull it off? The campaign begins after the 2018 midterm elections. “The Democrats will win the majority in the U.S. House of Representatives —” They are determined, more than ever, to take the fight in 2020 to Donald Trump. “You know, the Democrats are AWOL. They’re missing in action.” “Today, I am announcing my candidacy for president —” Biden enters the race as a clear front-runner, lifted by the positive feelings that so many Democrats have about his role during the Obama administration. “I’m— I’m paying for Joe, so don’t take his money.” [LAUGHTER] But there are persistent questions about just how ready he is for a campaign in 2020 and just how effectively he can defend his very, very long record in government. “I’m going to now direct this at Vice President Biden.” He is on the defensive over and over. “Do you agree today that you were wrong to oppose busing in America then?” “No.” Challenged by other candidates. “Are you forgetting—” “It’s automatic to be enforced.” ”—what you said two minutes ago?” Biden’s greatest difficulties come in the first states to vote, Iowa and New Hampshire. And these are places that really reward candidates with strong organization on the ground. Throughout the summer and the fall, we hear, over and over, from people in Iowa and New Hampshire, that Joe Biden does not have that kind of organization. And then the night of the caucuses happened. He comes in fourth place in Iowa. And when the campaign moves to New Hampshire, he fares even worse. He is in fifth place. Much of the political world, essentially, counts out Joe Biden. They see that his fund-raising has dried up. They see that his poll numbers have crashed. “Now we’re going on to South Carolina and win. And now we’re going to take this back.” And Biden’s campaign keep saying, wait until South Carolina, a real turning point. “Thank you. Thank you. Thank you, South Carolina.” When that moment of victory came in South Carolina, it seemed to remind millions of people, all at once, of why they liked Joe Biden in the first place and to remind them in a convincing enough way for many of them to change their minds about who they were going to vote for in a matter of days, leading to just a total turnaround in this race. “I am ending my campaign and endorsing Joe Biden.” Two major candidates almost immediately drop out of the race. Then comes Super Tuesday. He wins 10 of the 14 states, some of them by absolutely enormous margins. And that’s when Joe Biden goes from being the comeback kid to a strong front-runner once again. “Who’s ready to go to the center of the arena, who is our best shot to beat Donald Trump.” And from there, Joe Biden has only continued to widen his delegate lead. He persuaded the significant majority of Democratic voters that he was, by far, the strongest candidate to oppose Donald Trump in the general election. He put together a powerful coalition that combined some of the most loyal constituencies in the Democratic Party, especially African-Americans and women. “Folks, the vote is in your hands, not a joke. You can control this outcome.” With some of the newer constituencies that have supported Democrats since President Trump’s election, moderate suburban white voters who greatly preferred Joe Biden to Bernie Sanders. Biden has emerged as the likely Democratic nominee at exactly the moment that the coronavirus has brought the campaign almost to a halt. “That means we have to do testing. We have to get the testing kits up and ready.” “And we’ll lead with science.” Biden’s campaign did not run the strongest campaign operationally. He was not a flawless candidate. “Now, now, shush.” But a lot of voters knew him well enough, or felt they did, to look past a lot of that and to embrace him in the end as what they saw as a safe choice. This has been a wild campaign so far. And now, with the coronavirus, there are even more questions arising about the campaign going forward and the election. Go to nytimes.com/2020 to keep up with our reporters all around the country.