Joe Biden's withdrawal from the race for the White House leaves a gap atop the Democratic presidential ticket that the party is now rushing to fill.
Here is a look at potential replacements:
Kamala Harris
She seems like the obvious choice, and Biden has given her his endorsement.
US Vice President Kamala Harris, who has been a heartbeat away from the Oval Office since Biden's January 2021 swearing in, is well positioned to be the Democratic Party's standard-bearer.
The 59-year-old Harris, the daughter of a Jamaican father and an Indian mother, is a trailblazer.
She was the first Black person and the first woman to serve as California's attorney general, and then was the first US senator of South Asian descent.
She is now the first woman and first Black vice president.
During her career as a prosecutor, Harris had a reputation for being tough -- a trait she could use to advantage in a campaign expected to focus on crime and immigration.
But some progressive Democrats have been critical of her strict punishment of minor offenders, saying it disproportionately affected minorities.
Harris also suffers from a dismal approval rating, which could prompt Democrats to find another solution.
Gavin Newsom
There is no rule that a running mate automatically replaces the presidential candidate in the case of a withdrawal. This is why California Governor Gavin Newsom's name keeps popping up.
The 56-year-old Democrat, a former mayor of San Francisco, has been at the helm of the Golden State -- the most populous in the United States -- for five years, and has made it a haven for abortion access.
Newsom steadfastly supported Biden and dismissed talk of replacing him prior to the Democrat's withdrawal, but he has also made little secret of his own presidential ambitions.
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In recent months, he has increased his international travel, run multiple ads touting his record, and invested millions of dollars in a political action committee, fueling speculation that he will run in 2028. So why not 2024?
Gretchen Whitmer
Another possible Democratic candidate is Gretchen Whitmer, the 52-year-old governor of Michigan.
Her state has both a strong working-class population and major Black and Arab American communities -- all key groups of voters that Biden struggled to court.
Whitmer, a fierce critic of Trump, is perhaps best known for being the intended target of a kidnapping plot devised by a far-right militia group.
Michigan will be one of the crucial battleground states in the November 5 presidential election -- a strong argument, according to her supporters, for naming Whitmer as a candidate.
Josh Shapiro
Pennsylvania Governor Josh Shapiro leads the biggest swing state in November's race.
The 51-year-old, who was elected in November 2022 with a convincing victory over a conservative rival and took office in early 2023, previously was elected twice as the state's attorney general.
He condemned Catholic priests who had sexually abused thousands of children and prosecuted Purdue Pharma, the maker of the powerful opioid painkiller OxyContin.
Shapiro is an effective speechmaker and an avowed centrist -- qualities that could propel him to national office.
The rest
Other names circulating include Illinois Governor JB Pritzker, Maryland Governor Wes Moore and Kentucky Governor Andy Beshear, but their chances so far seem limited at best.
Senator Amy Klobuchar and Transportation Secretary Pete Buttigieg, who both ran against Biden in the 2020 primaries, have also been mentioned.