"The current president has cloaked America in darkness for far too long. Too much anger, too much fear, too much division," the former vice president said. "We can and will overcome this season of darkness."
Biden excoriated President Donald Trump and vowed that while he was accepting his party's nomination for president, he would work just as hard for those who didn't support him.
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"While I’ll be a Democratic candidate, I’ll be an American President," Biden said. "I will draw on the best of us, not the worst. I will be an ally of the light, not the darkness."
The former vice president spoke live to an empty darkened room near his home in Wilmington, Delaware. Supporters in cars filled a parking lot outside to watch on large screens. Protesters, supporting Trump, also were on hand. Fireworks burst overhead after he concluded.
Biden said the nation is facing four crises simultaneously, on the coronavirus pandemic, the ensuing recession, renewed demands for racial justice and climate change -- and that Trump has failed in every one of them.
"Our current president has failed in his most basic duty to the nation. He’s failed to protect us," Biden said. "And my fellow Americans, that is unforgivable."
If Trump is reelected, Biden warned more people will die from the COVID-19 pandemic, more businesses will shutter and more working people will struggle, even if the wealthiest one percent get another tax break.
"He’ll wake up every day believing the job is all about him, not about you," Biden said.
The final night of the DNC program also features appearances from Biden's family, including his son Hunter, who has struggled with addiction and is rarely seen in public. There was a moving tribute to his other son, Beau, who died of a brain tumor in 2015. And a video of his grandaughters attested to a love of ice cream sometimes hidden from their grandmother.
Democrats paid tribute to John Lewis, the civil rights leader and congressman who died last month, with Atlanta Mayor Keisha Lance Bottoms urging Americans to rise to his example.
"Congressman Lewis would not be silenced. And neither can we," she said. "We cannot wait for some other time, some other place, some other heroes. We must be the heroes of our generation."
America is ready, Biden said, paraphrasing Lewis, to "lay down the heavy burden of hate" and end systemic racism.
A group of 2020 Democratic also-rans appeared together via video to discuss Biden, with Cory Booker joking, "You could think of this like the interview on 'Survivor' with all the people who got voted off the Island."
This has been a long time coming for the 77-year-old Biden.
After a David-and-Goliath campaign against a powerful Republican in 1972, Biden entered the Senate as both its youngest member and one of its most tragic figures. His wife and baby daughter were killed in a car accident just weeks after his election and he almost decided to quit before even being sworn in.
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His story and style made the young Biden a natural potential candidate for higher office and he first seriously considered a White House bid in 1980. "I remember thinking: I have no business making a run for president," he later wrote in his memoir "Promises to Keep." "I was 37 years old...Am I flying too close to the sun?"
Biden decided not to run that year, nor in 1984, despite taking another serious look at it. And when he finally did pull the trigger in 1988, it ended in humiliation when he withdrew from the race after getting caught lifting some lines of his speeches from a British politician.
Cowed, Biden focused on his work in the Senate and didn't take another shot at the brass ring until 2008. He flamed out in Iowa, where he finished with less than one percent, but finished with the significant consolation prize of the vice presidency.
He explored another run in 2016, but opted to step aside for Hillary Clinton, citing the recent death of his son Beau. His 2020 bid got off to a poor start and many Democrats, including some close to Biden, privately predicted he would cap his career with another embarrassing loss.
He finished fourth in Iowa, fifth in New Hampshire, and second in New Hampshire before, in the course of a stunning few days, everything turned around. He rallied to a commanding victory in South Carolina then surged as the other moderate candidates in the race dropped out to endorse him.
"This is our moment, this is our mission," Biden said Thursday. "History will be able to say the end of this chapter of American darkness began tonight."
"This is a battle we will win," he continued, "and we'll do it together."
This story was originally published on NBCNews.com.