Former US Vice President Joe Biden had a strong showing in the early returns on Super Tuesday, as he was projected to sweep four Southern states: Tennessee, Alabama, North Carolina and Virginia.
Biden was also leading in five other states - Maine, Massachusetts, Arkansas, Minnesota and Oklahoma - as he appeared to be having a good night across the country.
Senator Bernie Sanders was declared the winner in his home state of Vermont, and was leading in early returns in Colorado. Senator Elizabeth Warren, meanwhile, was running in third in her native Massachusetts, and struggling to reach the 15 per cent threshold to receive delegates anywhere else.
Supporters of Democratic presidential hopeful former Vice President Joe Biden attend a Super Tuesday event in Los Angeles. Source: AFP
Michael Bloomberg, the former mayor of New York, appeared on the ballot for the first time on Tuesday. He was running either third or fourth in every state in early returns, though he did pick up a win in American Samoa.
Fourteen states are voting on Tuesday, with some 1,344 delegates at stake - more than a third of the total. The big prize is California, where Sanders hopes to score a major win with the aid of Latinos and young voters.
Vice President Biden seemed left for dead after he finished fourth and fifth in Iowa and New Hampshire, respectively. But he has revived his campaign over the last 72 hours, following a blowout win in South Carolina on Saturday. On Monday, he picked up endorsements from three former candidates - Pete Buttigieg, Amy Klobuchar and Beto O'Rourke.
"We need somebody who can beat Donald Trump," O'Rourke told a crowd in Dallas on Monday night. "In Joe Biden, we have that man. We have someone who is the antithesis of Donald Trump."
Vice President Biden was at a Roscoe's Chicken and Waffles in Los Angeles on Tuesday afternoon as Virginia and North Carolina were called in his favor. He is scheduled to address a crowd in Baldwin Hills on Tuesday evening. On Wednesday, Biden is set to attend a Hollywood fundraiser at the home of Sherry Lansing. Sen. Dianne Feinstein and her husband, Richard Blum, are co-hosting the event.
Senator Sanders, meanwhile, voted in Vermont on Tuesday morning and is holding a rally there this evening.
Mr Bloomberg spoke to a crowd in Palm Beach, Fla., were he said he had proven that he could "win the voters who will decide the general election."
Supporters of Senator Bernie Sanders attend his Super Tuesday event in Essex Junction, Vermont. Source: Getty Images North America
"No matter how many delegates we win tonight, we have done something no one else thought was possible," Bloomberg said. "In just three months, we've gone from 1% in the polls to being a contender for the Democratic nomination for president."
However, the Former New York Mayor is now reportedly reassessing his campaign for the Democratic presidential nomination, according to NBC News.
The Bloomberg campaign did not immediately respond on Tuesday to a request for comment.
The billionaire media mogul adopted a novel strategy for his White House bid, opting out of the first four nominating contests and hoping a $US500 million-plus ad blitz would generate a momentum-building series of wins in the 14-state Super Tuesday primaries.
Former New York City Mayor Mike Bloomberg speaking at the American Israel Public Affairs Committee Policy Conference. Source: Michael Brochstein/Sipa USA
"No matter how many delegates we win tonight, we have done something no one else thought was possible. In just three months, we've gone from just 1 per cent in the polls to being a contender for the Democratic nomination," his campaign said in a statement.
"Our number one priority remains defeating Donald Trump in November."
Rep. Tulsi Gabbard was projected to come in second in American Samoa, and take one delegate from the territory.
Meanwhile in Detroit, Michigan, where voters go to the polls on 10 March, Elizabeth Warren urged voters to tune out pundits' predictions.
"What I see happening is a lot of folks trying to turn voting into some complicated strategy," she said. "Prediction has been a terrible business. The pundits have gotten it wrong over and over... Here's my advice: cast a vote that will make you proud. Cast a vote from your heart. Vote for the person you think will make the best president of the United States."
