He's now President-Elect Joe Biden.
After winning Pennsylvania Saturday morning NBC News projects Joe Biden will be the 46th president of the United States. Biden's defeat of President Donald Trump positions him to lead a nation gripped by a historic pandemic and a confluence of economic and social turmoil.
Biden took to social media Saturday after the race was called in his favor.
"America, I’m honored that you have chosen me to lead our great country," Biden wrote. "The work ahead of us will be hard, but I promise you this: I will be a President for all Americans — whether you voted for me or not. I will keep the faith that you have placed in me."
Biden is planning to address the nation on Saturday night. His presidential campaign announced that Biden and his wife, Jill, and Vice President-elect Kamala Harris and her husband Doug Emhoff will appear at a drive-in rally outside the convention center in Wilmington, Delaware.
Biden's victory came after more than three days of uncertainty as election officials sorted through a surge of mail-in votes that delayed the processing of some ballots. Biden currently tallies 273 Electoral College votes with the win in Pennsylvania.
Biden was on track to win the national popular vote by more than 4 million, a margin that could grow as ballots continue to be counted.
With the projected victory Kamala Harris makes history as the first Black woman elected as vice president of the United States, shattering barriers that have kept men — almost all of them white — entrenched at the highest levels of American politics for more than two centuries.
The 56-year-old California senator is also the first person of South Asian descent elected to the vice presidency.
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The reaction to the news came swiftly from many sectors.
Within seconds of the race being called, a group at Black Lives Matter plaza outside the White House erupted in cheers.
Shouts of joy could also be heard around several New York City neighborhoods. Cars honked their horns as pedestrians lining the sidewalks clapped and cheered.
Hillary Clinton, who lost to Trump in the 2016 presidential election contest, took to social media after Biden was projected the winner.
"The voters have spoken, and they have chosen @JoeBiden and @KamalaHarris to be our next president and vice president," Clinton wrote. "It's a history-making ticket, a repudiation of Trump, and a new page for America. Thank you to everyone who helped make this happen. Onward, together."
Speaker of the House Nancy Pelosi responded to the election of President-elect Joe Biden and Vice President-elect Kamala Harris in a statement.
“Today marks the dawning of a new day of hope for America. A record-shattering 75 million Americans cast their ballots to elect Joe Biden President of the United States – a historic victory that has handed Democrats a mandate for action," she said.
Trump's campaign and Republicans already are mounting legal challenges in several states, although most are small-scale lawsuits that do not appear to affect many votes.
Trump reacted to news that Biden was declared the winner of the 2020 election by vowing to continue to fight the election results and repeating false claims of a rigged election.
"Beginning Monday, our campaign will start prosecuting our case in court to ensure election laws are fully upheld and the rightful winner is seated," Trump said in a statement.
Earlier Saturday, Trump had again tweeted the false claim that he had won the election, despite all evidence to the contrary. But in recent days, even some of Trump's Republican allies had denounced the president's claims that the election had been rigged. A key Republican senator stepped forward Friday saying he saw no evidence to support Trump’s baseless claim that Democrats are trying to “steal” the election and called the president's words “very disturbing.”
Sen. Pat Toomey of Pennsylvania said, "There’s simply no evidence anyone has shown me of any widespread corruption or fraud" to supported Trump's claim Thursday of fraud in balloting.
Mitt Romney added to the GOP chorus Friday slamming Trump's unsubstantiated claim. Romney, now a senator from Utah, said Trump was within his rights to request recounts and call for investigations where evidence of irregularities exists.
But Trump “is wrong to say the election was rigged, corrupt and stolen,″ Romney said on Twitter. Trump’s claim ”damages the cause of freedom here and around the world ... and recklessly inflames destructive and dangerous passions,″ Romney said.
The Associated Press contributed to this report.