Buoyed by strong support from black voters who are a crucial bloc in Democratic primaries, Mr. Biden emerged as a potential front-runner and the clear alternative to Mr. Sanders‘ vision for a dramatic makeover of America.
“They don’t call it Super Tuesday for nothing,” Mr. Biden told cheering supporters in Los Angeles. “We were told when we got to Super Tuesday it would be over. Well, it may be over for the other guy.”
Mr. Sanders, however, captured the biggest prize of the night, scoring big with young and minority voters on his way to winning California, according to The Associated Press.
Mr. Biden won in Texas, the second-biggest state of the night and one where he had led pre-primary polls.
However, Mr. Sanders was essentially tied with Mr. Biden in Maine with 81% of the precincts reporting early Wednesday morning.
Mr. Sanders defended his home turf in Vermont, and was projected to win Colorado and Utah as soon as the polls closed, underscoring his strength in the West.
Despite Mr. Biden’s success, which will be viewed as a setback to what Mr. Sanders describes as a political movement to reshape America, the Vermont socialist remained undaunted and defiant of the Democratic Party establishment, which he accuses of stealing the nomination from him in 2016.
“Tonight I tell you with absolute confidence we are going to win the Democratic nomination, and we are going to defeat the most dangerous president in the history of this country,” said Mr. Sanders, rallying his supporters in his home state. “What made this movement unique is we are taking on the corporate establishment. We are taking on the greed of Wall Street.”
Billionaire media mogul Michael R. Bloomberg’s night got off to a humiliating start.
The former New York mayor’s sole bright spot was his first victory, in American Samoa, the skimpiest delegate haul of the evening. Otherwise, he was getting embarrassed after squandering a chunk of his vast fortune on a campaign that started late in the race and bet big on Super Tuesday. In Virginia, which he had carpet-bombed with TV and internet ads, he mustered only about 10% of the vote.
The South Pacific island territory also gave Rep. Tulsi Gabbard of Hawaii her first delegate in her underdog run for the White House.
Mr. Biden, meanwhile, showed that his victory Saturday in South Carolina’s primary was not a fluke.
He racked up wins in Alabama, Arkansas, North Carolina, Massachusetts, Minnesota, Oklahoma, Tennessee and Virginia.
The swath of the South captured by Mr. Biden underscored his loyal following among black voters. He won a whopping 63% of the black vote in Virginia.
He also ran strong among voters who decided whom to support over the past few days. Early exit polls from 12 Super Tuesday states indicated that Mr. Biden won 47% of those who made up their minds just before the primary vote.
Democratic voters’ late move toward Mr. Biden appeared as a wave building against Mr. Sanders‘ socialist agenda.
The biggest prizes of the night were California, Texas and North Carolina, accounting for 754 of the 1,358 delegates up for grabs.
The ballot counting in California was expected to take days.
As the polls opened, the race already was starting to look like it was shaping up as a two-person contest between Mr. Sanders and Mr. Biden — pitting the party’s far-left wing against its somewhat more moderate establishment.
Mr. Bloomberg remained the wild card in the race after funneling $500 million into advertisements, half of which was dumped into the television and radio airwaves in the 15 states and territories that voted Tuesday.
Mr. Bloomberg said this week that he could emerge as a power broker at the Democratic National Convention if no one else in the race collects the 1,991 delegates needed to automatically win the nomination on the first ballot vote.
Despite the lackluster showing, Mr. Bloomberg declared a moral victory before most of the polls closed. He said he still has a grand plan to win the nomination and defeat President Trump.
“My fellow candidates spent a whole year focusing on the first four states,” Mr. Bloomberg said. “I was out campaigning against Donald Trump in the states where the election will actually be decided, like Wisconsin and Michigan and Pittsburgh and Ohio and North Carolina and Florida.”
Larry Sabato, head of the Virginia Institute of Politics, said Mr. Bloomberg might need to rethink his bid if he fell short of collecting 15% of the vote in Virginia.
“After Bloomberg’s massive sums in VA — mainly for TV ads that you couldn’t avoid no matter what you watched — it’s an embarrassment not to get over 15% statewide,” Mr. Sabato said in a Twitter post. “A hint to say bye-bye?”
Sen. Elizabeth Warren of Massachusetts, who has vowed to stay in the race no matter what, continued her downward trajectory by finishing third behind Mr. Biden and Mr. Sanders in her home state and not finishing in the top two in any state.
Mr. Biden resuscitated his campaign with his first primary win in South Carolina and has since scored the backing of several of his former rivals: Sen. Amy Klobuchar of Minnesota, former South Bend, Indiana, Mayor Pete Buttigieg and former Rep. Beto O’Rourke of Texas.
The collapse of the Buttigieg and Klobuchar campaigns helped declutter the “moderate” lane in the primary contest and gave Mr. Biden a clearer path to the nomination.
Still, Mr. Sanders held a delegate lead after stringing together a close second-place finish in Iowa and a pair of first-place finishes in New Hampshire and Nevada. He was widely expected to expand his lead Tuesday.
Mr. Sanders‘ fundraising operation also has been unparalleled. His camp announced this week that he raised $46 million in February and reserved airtime in five of the states set to vote next week.
The biggest source of his strength has come from young and very liberal voters, whereas Mr. Biden has been the top pick of black and less liberal voters.
That fueled speculation that the race has begun to split along geographical lines. Mr. Biden’s stronghold appears to be the South, while Mr. Sanders has polled better in states that traditionally vote Democratic in the general election — close to the split in the 2016 race between Mr. Sanders and eventual nominee Hillary Clinton.
The race now moves to the March 10 contests, in which a half-dozen states — including Michigan, Washington and Missouri — with a total of 320 delegates will be up for grabs.