Never in recent US election history has the vice presidential pick carried as much attention and intrigue as with the presumptive Democratic nominee Joe Biden.
If he wins in November, Mr Biden would be the oldest president to take office, at age 78, making it uncertain that he would seek a second term in 2024.
This has put more emphasis on his choice for running mate as both someone who is "ready on day one" and the likely nominee for the Democratic Party in four years.
Last March, Mr Biden pledged to pick a woman for the vice-presidential spot and his campaign is vetting almost a dozen.
This process will conclude in a matter of weeks and Mr Biden is expected to announce his choice in early August, before the party convention in Wisconsin on August 17.
Recent protests in the US would make a black woman an unsurprising guess.
The main contenders for the position can be ranked as follows:
Kamala Harris
The senator from California is seen as a front-runner, a status that she has solidified after the continuing Black Lives Matters protests across the US.
The debate on racism that followed the killing of George Floyd at the hands of police in Minnesota has increased the likelihood of a black woman being picked for the position.
Ms Harris, the only black woman elected to the Senate, is regarded as a VP favourite for Democrats.
Despite questions about her record as attorney general of California, she has pivoted to the left, pushing for police reform and sponsoring a Covid-19 stimulus bill with the Vermont senator Bernie Sanders.
A Monmouth University poll released in June found her a top choice, with 28 per cent favouring her pick.
Ms Harris's age, 55, name recognition on the national stage and fund-raising prowess have helped her case.
Elizabeth Warren
Elizabeth Warren, a senator from Massachusetts, is a liberal firebrand who appeals to progressives and the Democratic party base and is another strong contender for the VP position.
She remains the best-known name on the national stage and is seen favourably by 45 per cent of registered voters, a recent poll by The New York Times suggests.
Ms Warren would help Mr Biden galvanise young people, and the two have been speaking routinely during the search.
Val Demings
The Florida congresswoman, a lesser-known name on the national stage, has a unique background as a former police chief, a descendant of slaves and the daughter of a maid and janitor.
Ms Demings became more widely known during the impeachment hearings of US President Donald Trump, the trial of which she managed.
She is well-spoken and could help Mr Biden to win in Florida in November.
Tammy Duckworth
The senator from Illinois is an Iraq-war veteran and double amputee who can help Mr Biden to attract military votes and improve his numbers in the Midwestern states.
Frank Bruni of The New York Times called her an obvious best choice for vice president and she was endorsed on Monday by VoteVets, a political action committee of veterans against Mr Trump.
With the news focus on alleged bounties offered by Russia for attacks on US troops in Afghanistan, the veteran has been on the offensive against Mr Trump.
If picked, Ms Duckworth would be the first Asian American on a national presidential ticket.
Keisha Lance Bottoms
The mayor of Atlanta, Georgia, was one of the earliest endorsers of Mr Biden, in June last year.
Ms Bottoms was praised by the House's majority whip and highly respected African-American congressman Jim Clyburn.
She received national attention during the George Floyd protests in Atlanta, and could help Mr Biden to win Georgia, a state the Democrats have not won since 1992.
Michelle Lujan Grisham
The governor of New Mexico is not known nationally, but is the only Latina on the list.
Ms Grisham has been highly commended and profiled in Rolling Stone for her job tackling the Covid-19 pandemic.
Her strengths are in bringing executive experience, offering geographical balance for the ticket and helping Mr Biden among Hispanic voters, where his support lags behind former nominee Hillary Clinton.
Susan Rice
A former national security adviser and ambassador to the UN, Susan Rice brings foreign policy experience to the ticket.
Having served along Mr Biden in the Obama presidency, she is also seen as a loyal and a safe pick.
But the former ambassador has not held elected office, a criterion that, according to CNN, Mr Biden wants in his running mate.
Gretchen Whitmer
The Michigan governor and rising star in the party would help Mr Biden in the Midwest, and at 48, would bring a generational balance to the ticket.
But not being from a minority and a recent controversial Facebook post from her husband have reduced her chances.
Stacey Abrams
The former candidate for Georgia governor met Mr Biden in March 2019, triggering speculation then about her VP chances.
But despite being a national name and able to drive high African-American turnout, the lack of executive experience and the fact that the campaign has not been in touch with her makes her an unlikely pick.
Tammy Baldwin
The senator from Wisconsin would help Mr Biden in the Badger state, which Democrats lost in 2016.
Ms Baldwin would also be the first gay person on a national ticket.
