Joe Biden won 10 states and Bernie Sanders four as Democratic presidential hopefuls battled for delegates on Super Tuesday.

It was a night that exceeded expectations for the resurgent Biden, upsetting Sanders in Texas and outperforming polls across the board. Michael Bloomberg has since dropped out and endorsed Biden. The bright spot for Sanders was the delegate-rich California, which he was on course to win comfortably. 

Who were the Super Tuesday winners and losers?

Fourteen states, plus American Samoa and Democrats Abroad, voted on a day that looks set to reshape the contest to become the Democratic nominee to take on Donald Trump in November's presidential election as a two-horse race. 

While the former vice president won the most states, the all-important delegates are allocated proportionately both statewide and by district, so the final count is likely to be close. 

With some delegates still to be allocated after Super Tuesday, the Associated Press delegate tracker puts Biden on 566, Sanders on 501 and Elizabeth Warren on 61.

Biden exceeds expectations

"It's a good night and it seems to be getting even better!" Biden told supporters in California. "They don't call it Super Tuesday for nothing!"

Biden, whose campaign was written off just days ago, won the battleground states of Texas, Virginia and North Carolina as well as Alabama, Oklahoma, Minnesota, Arkansas, Massachusetts, Maine and Tennessee. 

The victory in Texas was the biggest shock, and one which will hurt Sanders most. The 228 delegates will be shared fairly equally, possibly with some heading to Bloomberg, but the Vermont senator had been expected to win after spending and campaigning heavily in the state. 

Biden, 77, has been boosted by the decisions of Pete Buttigieg and Amy Klobuchar to drop out of the race and give him their endorsements, as well as a big win in Saturday's South Carolina primary.

He showed strength with black and older voters, winning in the Northeast, the upper Midwest and sweeping the South. Turnout increased markedly, to his benefit, in Virginia and North Carolina.

Sanders wins California 

Sanders won California, Colorado, Utah and Vermont, racking up delegates in every state but failing to meet expectations.

"Tonight I tell you with absolute confidence, we are going to win the Democratic nomination," Sanders told supporters. "And we are going to defeat the most dangerous president in the history of the country."

The 78-year-old is banking on a big win in California, which has 415 delegates, to make up for losses elsewhere and particularly the loss in Texas. He held a lead over Biden of around 10 points with almost half the votes counted, but the final result won't be known for several days.

Sanders continued to win young voters in large numbers, but so far does not appear to have brought more people to the ballot box – a key part of his electability argument. 

Bloomberg, Warren struggle

Billionaire Bloomberg, who has spent around 500 million U.S. dollars on his campaign, won American Samoa and looks likely to finish third in California and Texas, but underperformed his polling in several other states. 

He dropped out of the race on Wednesday after struggling to even make the 15-percent threshold to win delegates in some states where he spent heavily.

Warren missed the threshold for delegates in several states, and finished a disappointing third in her home state of Massachusetts. 

She has not won any of the opening 18 contests, and will be under pressure to drop out of the race after again failing to win over voters.