Virtually every sentence of his 22-minute speech was designed to present a sharp, yet hopeful, contrast with the Republican incumbent.

In his strongest remarks of the campaign, Biden spoke both of returning the United States to its traditional leadership role in the world and of the deeply personal challenges that shaped his life.

“Here and now I give you my word: If you entrust me with the presidency, I will draw on the best of us not the worst. l’ll be an ally of the light, not the darkness," Biden said. "Make no mistake, united we can and will overcome this season of darkness in America.”

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For the 77-year-old Biden, the final night of the Democratic National Convention was bittersweet. He accepted a nomination that had eluded him for over three decades because of personal tragedy, political stumbles and rivals who proved more dynamic.

But the coronavirus denied him the typical celebration, complete with the customary balloon drop that both parties often use to fete their new nominees. Instead, Biden spoke to a largely empty arena near his Delaware home.

Afterward, fireworks lit the sky outside the arena where supporters waited in a parking lot, honking horns and flashing headlights in a moment that finally lent a jovial feel to the event.

The keynote address was the speech of a lifetime for Biden, who would be the oldest president ever elected if he defeats Trump in November. Trump, who is 74, publicly doubts Biden's mental capacity and calls him “Slow Joe,” but with the nation watching, he was firm and clear.

Still, the convention leaned on a younger generation earlier in the night to help energize his sprawling coalition.

Above all, Biden focused on uniting the nation as Americans grapple with the long and fearful health crisis, the related economic devastation, a national awakening on racial justice — and Trump, who stirs heated emotions from all sides.

Biden's positive focus Thursday night marked a break from the dire warnings offered by former President Obama and others the night before. The 44th president of the United States warned that American democracy itself could falter if Trump is reelected, while Biden's running mate, Kamala Harris, the 55-year-old California senator and daughter of Jamaican and Indian immigrants, warned that Americans’ lives and livelihoods were at risk.

Biden’s call for unity comes as some strategists worry that Democrats cannot retake the White House simply by tearing Trump down, that Biden needs to give his sprawling coalition something to vote for. That’s easier said than done in a modern Democratic Party made up of disparate factions that span generation, race and ideology.

Thursday’s convention served as a national reintroduction of sorts that drew on some of the most painful moments of his life.

“I know how mean and cruel and unfair life can be sometimes,” Biden said. He added: “I found the best way through pain and loss and grief is to find purpose.”

Trump’s Republican Party is expected to deliver a message next week squarely focused on the president's most loyal supporters..

Biden summed up his view of the campaign: “We choose a path of becoming angry, less hopeful and more divided, a path of shadow and suspicion, or we can choose a different path and together take this chance to heal.”