Candidates jostling to lead the Democratic Party into the US presidential election will face a first real test of their popularity among black voters in Saturday's South Carolina primary.
Just three days later, on all-important "Super Tuesday," 14 states hold nomination votes.
So where do the top seven candidates stand as the party struggles to find a leader who can unite its competing factions and defeat President Donald Trump in November?
Democratic presidential candidate Senator Bernie Sanders at a campaign event in North Charleston. Source: AAP
Bernie Sanders
Sanders, 78, has been the clear winner of the nomination battle so far, emerging as the frontrunner after early votes in Iowa, New Hampshire and Nevada.
His success has generated alarm among party moderates who fear his leftist socialism and believe he is an easy target for Trump.
In South Carolina, the Sanders surge could see him finish second or even first - giving him huge momentum heading into Super Tuesday.
Joe Biden
Biden, Barack Obama's vice president, is proud of the loyalty he has earned among many black voters and he is favored to win South Carolina, but his campaign has faltered badly.
He has ceded much support in the state to Sanders and Tom Steyer, triggering concern from his supporters that the 77-year-old is a busted flush.
Only a decisive victory on Saturday could save Biden, whose performances in TV debates and poor results in early states have knocked him far off track.
Michael Bloomberg
Billionaire Bloomberg, 78, is not on the ballot in South Carolina as the former New York mayor focuses on California, the single biggest delegate prize, and other Super Tuesday states.
But the late-starter is a major contender in the overall race, boosted by his vast, self-financed campaign budget - he has poured a staggering $500 million into advertising, a record.
Democratic presidential candidate former New York City Mayor Michael Bloomberg. Source: AAP
He says he offers the best chance of defeating Trump.
Pete Buttigieg
Aged just 38, the former mayor of South Bend, Indiana has generated major buzz with his unflustered and professional approach, and Buttigieg's campaign took center stage with his narrow win in the Iowa caucuses.
South Carolina is a tricky hurdle as he scores poorly in polling among black voters -- a key Democratic demographic. A weak result there and on Super Tuesday could pop the Buttigieg bubble.
Elizabeth Warren
After disappointing results in the first three contests, the 70-year-old senator from Massachusetts has tried to regain ground with effective attacks on Bloomberg in the past two debates.
As a progressive, Warren has suffered from Sanders' rise, and her prospects look to be fading as she currently polls fourth in South Carolina.
Tom Steyer
Billionaire activist Steyer, 62, has made little impact on the overall race despite his wealth. But he has relentlessly targeted black voters and Saturday's primary is a chance for him to secure a valuable third-place finish.
In Tuesday's TV debate, he made a point of boasting he was the only candidate who believed in reparations for slavery.
Democratic presidential candidates Elizabeth Warren, Pete Buttigieg, Mike Bloomberg, Bernie Sanders, Amy Klobuchar and Tom Steyer Source: AAP
Amy Klobuchar
In Tuesday's often bad-tempered contest, centrist Senator Klobuchar, 59, strikes a more balanced tone and she has attracted some positive reviews of her debate performances.
But she risks finishing sixth in South Carolina, and will face further pressure to drop out.
