White House hopeful Joe Biden named Kamala Harris as his running mate Tuesday, a landmark pick that puts the senator from California in contention to become America's first female, and first black vice president.
Biden's announcement capped a months-long search for a Democratic partner to challenge President Donald Trump in November.
"I have the great honor to announce that I've picked @KamalaHarris -- a fearless fighter for the little guy, and one of the country's finest public servants -- as my running mate," Biden, 77, said on Twitter.
"I'm proud now to have her as my partner in this campaign."
The decision, announced in typical 2020 style on social media, was a crucial moment for Biden as he aims to build a broad coalition of voters to oust Trump from the White House.
Harris, who at 55 is two decades Biden's junior, could appeal to women voters, particularly those in the US suburbs who have been leaning away from Trump. The former California attorney general also personifies the diversity seen as key to building enthusiasm for the Democratic ticket.
Taking to Twitter shortly after the announcement, Harris -- who ran for the 2020 Democratic presidential nomination against Biden -- said she was "honored" to now join him as nominee for vice president, and would "do what it takes" to help him win.
"@JoeBiden can unify the American people because he's spent his life fighting for us. And as president, he'll build an America that lives up to our ideals," she wrote.
For Harris, being elevated onto a Democratic presidential ticket is the political moment of a lifetime. And if they win, the telegenic but tough Californian becomes the automatic frontrunner in the race for the 2024 or 2028 Democratic nomination.
Biden, who is three years older than Trump, would be the oldest person to take the office, and there is broad speculation that should Biden win, he would serve a single term and groom his deputy to succeed him.
Biden is likely confident that Harris has the policy chops and the governing experience to help lead on day one, and immediately step into the job as president if needed.
Trump poured scorn on Biden's announcement, saying he was "surprised" at his choice given Harris's lackluster performance in the Democratic nomination race.
"She did very poorly in the primaries" Trump told reporters at the White House. "And that's like a poll."
He went on to attack Harris for her role in the bruising confirmation hearings of Supreme Court Justice Brett Kavanaugh, calling her "the meanest, the most horrible, the most disrespectful of anybody in the US Senate."
But Biden's pick of Harris drew ringing endorsements from other quarters -- including from Barack Obama, America's first black commander in chief.
"I've known Senator @KamalaHarris for a long time. She is more than prepared for the job," tweeted Trump's predecessor.
"This is a good day for our country. Now let's go win this thing."
Harris has been a barrier-breaker for much of her political career.
Her parents were immigrants to the United States -- her father from Jamaica, her mother from India. She was the first black woman elected as California's attorney general, and only the second black woman, and the first woman of South Asian heritage, to be elected to the US Senate.
Biden's team stated that the two Democrats will deliver remarks Wednesday in Wilmington, Delaware as they kick off their joint campaign.
Next week the party convenes its Democratic National Convention -- almost entirely online due to the coronavirus pandemic -- when Biden and Harris will both deliver acceptance speeches.
Harris had clashed with Biden during the first Democratic debate of the 2020 race, chiding the former senator over his opposition to 1970s busing programs that forced integration of segregated schools.
It provided her with a breakout moment which proved short-lived: Harris dropped out of the race in December 2019 and endorsed Biden in March.
Despite their debate fireworks, Biden has made it clear he does not hold a grudge, describing Harris as a "first-rate intellect, a first-rate candidate and a real competitor."