WILMINGTON, Del. >> Joe Biden vowed to unite an America torn by crisis and contempt tonight, accepting the Democratic presidential nomination that had eluded him over three decades because of personal tragedy, political stumbles and rivals who proved more dynamic. Contrasting himself with President Donald Trump, he declared, “I’ll be an ally of the light, not our darkness.”

The past hurdles fell away as Biden addressed his fellow Democrats and millions of Americans at home who he hopes will send him to the White House to replace Trump — though his triumphant moment was drained of immediate drama by the coronavirus pandemic, which left him speaking to a nearly empty arena rather than a joyously cheering crowd.

In a race filled with Trump’s insults and name-calling, Biden declared, “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 our darkness.”

“And make no mistake, united we can and will overcome this season of darkness in America.”

Fireworks lit the sky outside as the convention ended, giving a celebratory feel at last to the affair.

In his acceptance speech, Biden highlighted both his world view and a series of deeply personal challenges that shaped his life. On issues big and small, the 77-year-old Democrat presented a sharp contrast to the Republican president, but maintained a hopeful tone throughout.

Trump, who is 74, publicly doubts his mental capacity and calls him “Slow Joe,” but with the nation watching, he was firm and clear.

The pandemic has shaken the nation and fundamentally altered the campaign. But Biden pointed to the public health emergency and the severe economic fallout to turn traits previously seen as vulnerabilities, notably a long career spent in elected office, into an advantage by presenting himself as a competent leader in a moment that Democrats say cries out for one in the White House.

The night’s keynote address was the speech of a lifetime for Biden, who would be the oldest president ever elected if he defeats Trump in November. But his convention leaned on a younger generation earlier in the night to help energize his sprawling coalition.

Tammy Duckworth, an Illinois senator who lost both legs in Iraq and is raising two young children, said Biden has “common decency.”

Cory Booker, only the ninth African American senator in U.S. history, said Biden believes in the dignity of all working Americans.

And Pete Buttigieg, a 38-year-old openly gay military veteran from Indiana, noted that Biden came out in favor of same-sex marriage as vice president even before President Barack Obama did.

“Joe Biden is right, this is a contest for the soul of the nation. And to me that contest is not between good Americans and evil Americans,” Buttigieg said. “It’s the struggle to call out what is good for every American.”

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 tonight 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 the daughter of Jamaican and Indian immigrants, warned that Americans’ lives and livelihoods were at risk.

Biden’s Democratic Party has sought this week to put forward a cohesive vision of values and policy priorities, highlighting efforts to combat climate change, tighten gun laws and embrace a humane immigration policy. They have drawn a sharp contrast with Trump’s policies and personality, portraying him as cruel, self-centered and woefully unprepared to manage virtually any of the nation’s mounting crises and policy challenges.

Voting was a prime focus of the convention today as it has been all week. Democrats fear that the pandemic — and the Trump administration — may make it difficult for voters to cast ballots in person or by mail.

Comedian Sarah Cooper, a favorite of many Democrats for her videos lip syncing Trump’s speeches, put it bluntly: “Donald Trump doesn’t want any of us to vote because he knows he can’t win fair and square.”

Biden’s call for unity comes as some strategists worry that Democrats cannot retake the White House simply by tearing Trump down; 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.

Though he has been in the public spotlight for decades, much of the electorate knows little about Biden’s background before he began serving as President Barack Obama’s vice president in 2008.

Today’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.”

As a schoolboy, Biden was mocked by classmates and a nun for a severe stutter. He became a widower at just 30 after losing his wife and infant daughter to a car accident. And just five years ago, he buried his eldest son who was stricken by cancer.

From such hardship, Biden developed a deep sense of empathy that has defined much of his political career. And throughout the convention, Biden’s allies testified that such empathy, backed by decades of governing experience, makes him the perfect candidate to guide the nation back from mounting health and economic crises.

His allies today included Brayden Harrington, a 13-year-old boy from Concord, New Hampshire. The boy said he and Biden were “members of the same club,” each with a stutter they’re working to overcome.

He noted that Biden told him about a book of poems he liked to read aloud to practice his speech and showed the boy how he marks his speeches so they’re easier to read aloud.

“I’m just a regular kid, and in a short amount of time, Joe Biden made me more confident about a thing that’s bothered me my whole life,” Harrington said.

The end of the carefully scripted convention now gives way to a far less-predictable period for Biden and his Democratic Party as the 2020 election season speeds to its uncertain conclusion. While Election Day isn’t until Nov. 3, early voting gets underway in several battleground states in just one month.

Biden has maintained a polling advantage over Trump for much of the year, but it remains to be seen whether the Democratic nominee’s approach to politics and policy will genuinely excite the coalition he’s courting in an era of uncompromising partisanship.

Trump’s Republican Party is expected to deliver a far more divisive message next week as the GOP hosts its own national convention.

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.”