Senator Kamala Harris of California is interviewed after the second night of the first Democratic primary debate in Miami, Florida, the United States, on June 27, 2019. Photo: Xinhua

US Presidential hopeful Joe Biden named Senator Kamala Harris, a former rival in the White House race, as his running mate Tuesday, marking a historic first for American women of color.

Biden's Tuesday's announcement capped a months-long search for a Democratic partner to challenge US President Donald Trump in November.

Harris, who would become America's first female and first black vice president if elected, is a "fearless fighter for the little guy, and one of the country's finest public servants," Biden, 77, said in revealing his running mate.

"I'm proud now to have her as my partner in this campaign."

The decision, which was 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 younger voters and women, particularly those in the suburbs who have been fleeing Trump.

The former California attorney general is the first person of Indian descent in the running mate role, and personifies the diversity seen as key to building enthusiasm for the Democratic ticket, particularly in a year marked by a historic reckoning on race.

She is the third female vice presidential nominee for a major party, after the groundbreaking but unsuccessful runs of Democrat Geraldine Ferraro in 1984 and Republican Sarah Palin in 2008.

Harris, who ran for the 2020 Democratic presidential nomination against Biden, said she was "honored" to join the ticket 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 tweeted.

For Harris, being elevated onto a presidential ticket is the political moment of a lifetime. And if they win, the telegenic but tough Californian would almost certainly become the frontrunner in the race for the 2024 or 2028 Democratic nomination.

Biden would be the oldest person to take the office, and there is broad speculation that should Biden win, he would serve one four-year term and groom his deputy to succeed him.

AFP