Democratic White House nominee Joe Biden closed out the carefully scripted, virtual 2020 Democratic National Convention on Thursday, achieving a pinnacle in an unfinished quest that has spanned three decades and been marred by personal tragedy and political stumbles.

»Read Joe Biden’s acceptance speech.

“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,” Biden declared. “I’ll be an ally of the light, not our darkness. And make no mistake, we’ll overcome this season of darkness in America.”

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Biden delivered his acceptance speech before a mostly empty auditorium near his Delaware home, vowing that on the first day of his presidency, he would implement “a national mandate to wear a mask.

“The current president has failed in the most basic duty to protect us,” Biden said, referring to the coronavirus pandemic that has shaken the nation and fundamentally altered the campaign. “That is unforgivable.”

Before Biden’s appearance, 13-year-old Brayden Harrington gave an emotional speech about how the former vice president helped him overcome a difficult challenge.

“We stutter,” Brayden said. The Concord, New Hampshire, teen got stuck briefly on the “s” sound and bravely worked his way through the word. His face showed strain but also determination to force out the sound.

“It’s really amazing to hear that someone became vice president” despite stuttering, Brayden said. “He told me about a book of poems by Yeats that he would read out loud to practice.”

Brayden Harrington speaks during the fourth night of the Democratic National Convention.

Thursday night’s keynote address was the speech of a lifetime for Biden, who at 77 would be the oldest president ever elected if he defeats Donald Trump in November. The convention leaned on a younger generation earlier in the night to help energize his sprawling coalition.

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

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Andrew Yang, a 45-year-old Asian American political outsider whose love of math inspired millions during the primaries, cast Biden as a leader capable of digging America out of “a deep dark hole.”

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

Atlanta Mayor Keisha Lance Bottoms helped kick off the fourth night of the DNC by paying tribute to the late John Lewis.

“We know how important it is that we elect real leaders like Joe Biden and Kamala Harris, people of honor and integrity, who hold justice close to their hearts and believe that the lives of my four black children matter,” said Atlanta Mayor Keisha Lance Bottoms. She introduced a tribute to John Lewis, the Georgia congressman and civil rights leader who died last month.

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Senator Kamala Harris gave her official acceptance speech for vice president nomination.

President Donald Trump will formally be renominated as his party’s candidate during the virtual Republican National Convention next week.