Joe Biden, the Democratic Party's presumptive 2020 nominee for president, will be joined on the ticket by Senator Kamala Harris (D-CA), who will serve as his running mate.
The choice of a running mate has added significance this year because of Biden's age. He turns 78 on November 20 and would be the oldest man ever to assume the office if he defeats Trump, as polls predict.
"The vice-presidential pick this year is so much more important than it normally is because people expect Biden to only serve one term," said David Barker, a professor of government at American University.
"And so whomever he picks as vice president is likely to be the next Democratic candidate for president in four years," Barker said.
Harris, the daughter of a Jamaican-born father and Indian-born mother, served as a district attorney in San Francisco before becoming attorney general of California, the first woman to hold the post in the most populous US state.
She was elected to the Senate in 2016, just the second black woman elected to the body and the first woman of South Asian heritage.
Harris challenged Biden for the Democratic nomination but dropped out of the race in December 2019 and threw her support behind Biden, the former vice president and senator from Delaware, in March.
Biden and Harris clashed during an early Democratic primary debate but he appears not to hold it against her.
Rapper Sean "Diddy" Combs led more than 100 prominent African-American men Monday in penning an open letter urging presidential candidate Joe Biden to choose a woman of color as his running mate.
President Donald Trump said earlier on Tuesday that some men may feel "insulted" by his Democratic rival Joe Biden's commitment to choose a woman as his vice presidential candidate.
"He roped himself into a certain group of people," Trump told Fox Sports Radio in an early morning phone-in interview.
"Some people would say men are insulted by that and some people would say it is fine," Trump said.
Declaring that he wants a government as diverse as the country itself, Biden committed early in his campaign, in March, that he would name a woman on the ticket.
Only two other women have been nominated vice presidential candidates -- Sarah Palin by the Republican party in 2008 and Geraldine Ferraro by the Democrats in 1984 -- and neither made it into the White House. No woman has won the presidency either.
In the radio interview, Trump praised his own vice president, Mike Pence, but said bluntly: "people don't vote for the vice president, they really don't."
"You can pick a George Washington to be a vice president. Let's pick up Abraham Lincoln, coming back from the dead. They just don't seem to vote for the vice president."
(with additional reporting from AFP)