COLUMBIA, S.C. — Joseph R. Biden Jr. scored a decisive victory in the South Carolina primary on Saturday, reviving his listing campaign and establishing himself as the leading contender to slow Senator Bernie Sanders as the turbulent Democratic race turns to a slew of coast-to-coast contests on Tuesday.
Propelled by an outpouring of support from South Carolina’s African-American voters, Mr. Biden easily overcame a late effort by Mr. Sanders to stage an upset. The victory in a state long seen as his firewall will vault Mr. Biden into Super Tuesday, where polls open in just over 48 hours, as the clear alternative to Mr. Sanders for establishment-aligned Democrats.
Mr. Biden, the former vice president, captured just under 50 percent of the vote, well ahead of Mr. Sanders, who had 20 percent. Tom Steyer, the California billionaire, was a distant third, followed by Pete Buttigieg and Senator Elizabeth Warren of Massachusetts. The victory enabled Mr. Biden to significantly narrow Mr. Sanders’s pledged delegate lead, but he did not appear poised to overtake him.
Mr. Biden, in an exuberant victory speech on Saturday night, looked ahead to a long, ideological struggle and made repeated arguments against Mr. Sanders, though not by name.
He said voters faced a momentous choice in the coming days. Democrats, Mr. Biden argued, wanted results rather than revolution, improvements to the Affordable Care Act rather than a disruptive transformation of the health care system, and a candidate who would “take on the N.R.A. and gun manufacturers and not protect them.”
“If Democrats want a nominee who’s a Democrat, a lifelong Democrat, a proud Democrat, an Obama-Biden Democrat, join us,” Mr. Biden said, adding, “We have the option of winning big or losing big. That’s the choice.”
As much as the results here offered new life to Mr. Biden, the one-time front-runner, they dealt a perhaps fatal blow to two moderates, Mr. Buttigieg, the former mayor of South Bend, Ind., and Senator Amy Klobuchar. Both had been hoping to overtake Mr. Biden as the candidate of the party’s center, but again proved unable to win nonwhite voters; Mr. Buttigieg received only 2 percent of support from black voters, according to early exit polls.
Perhaps even more consequentially, Mr. Biden’s triumph here also increased pressure on Michael R. Bloomberg to best Mr. Biden in the 15 states and territories voting Tuesday — or consider exiting the race.
Ms. Warren, a progressive rival to Mr. Sanders, also showed no strong appeal to African-American voters in the Republican-leaning state. But unlike the moderate candidates, Ms. Warren was unlikely to face similar pressure to make way for Mr. Biden, and some party leaders hope she will stay in the race and complicate Mr. Sanders’s efforts to consolidate the left.
Mr. Biden also overcame a challenge from Mr. Steyer, a former hedge fund investor who poured millions of dollars into courting black voters, and in some cases putting influential state lawmakers on his campaign payroll. But Mr. Steyer fell far short of the breakthrough his campaign believed was possible, and several hours after the polls closed he dropped out of the race.
For Mr. Biden, 77, the victory here was a moment to savor.
Low on cash and without a victory in the first three contests, Mr. Biden desperately needed South Carolina, a state for which he has long had a personal affection, to resurrect his third and perhaps final quest for the presidency.
Facing a humiliating fifth-place finish in New Hampshire earlier this month, Mr. Biden flew out of the New England cold before the polls had even closed there and effectively staked his campaign on South Carolina, telling supporters in Columbia that evening that he was counting on the state’s more racially diverse set of voters to offset his dismal showing in the first two states, both heavily white.
Then, after finishing a distant second to Mr. Sanders in Nevada, he came directly to South Carolina. He campaigned almost exclusively here while other Democrats fanned out across the much larger map of states that vote Tuesday.
In the debate this week, Mr. Biden promised to win South Carolina and projected confidence that he would prevail with African-Americans. He did both, claiming black voters with 64 percent, far better than Mr. Sanders’s 15 percent, exit polls showed.
The results here represented at least an interruption of what had loomed as a march to the nomination by Mr. Sanders. South Carolina was the first state where Mr. Sanders did not finish at the top, and his distant second to Mr. Biden came even after he had made a late effort to score a win.
Though Mr. Biden had led in every poll of South Carolina, Mr. Sanders, after winning in a landslide in Nevada, decided to try to deliver a finishing blow against Mr. Biden. Mr. Sanders increased his television advertising in the state and intensified his campaign schedule, with the goal of denying Mr. Biden the chance to reignite his candidacy and perhaps wrapping up the nomination fight by the middle of March.
Addressing supporters in Virginia, Mr. Sanders, 78, acknowledged Mr. Biden’s success in South Carolina and advised his audience to prepare for the ups and downs of a long campaign. “That will not be the only defeat,” Mr. Sanders said of South Carolina. “There are a lot of states in this country, nobody wins them all.”
But ticking off his victories so far, Mr. Sanders also pointed in a confident tone toward Tuesday’s primaries as the next frontier.
Ms. Warren, at a rally in Houston, also looked ahead to those contests. “I’ll be the first to say that the first four contests haven’t gone exactly as I’d hoped,” she told supporters. “But Super Tuesday is three days away and we’re looking forward to gaining as many delegates to the convention as we can.”
Having carried South Carolina as a kind of favorite-son candidate, Mr. Biden is counting on that result to ripple throughout the region and help him recover some of the support from black voters elsewhere that he lost in recent months, largely to Mr. Bloomberg. He needs voters to shift back in his direction quickly if he is to edge ahead of Mr. Sanders in enough states to deliver a strong showing on Super Tuesday.
But absent an overwhelming wave of new support for Mr. Biden, the best-case scenario for his campaign may still be a daunting one: a monthslong battle against a tireless opponent with superior financial and organizational resources at his disposal, and a formidable well of support from the Democratic Party’s left wing.
Mr. Sanders has had a weekslong head start in a number of key Super Tuesday states where early voting has long been underway, including California, which on its own could give Mr. Sanders a sizable lead in the national delegate count.
Mr. Biden is also likely to face pressure and scrutiny from his fellow Democrats of a kind he has not received in weeks, in a test of whether a candidate who has spent most of the race grasping for his political footing can achieve sustained momentum for the first time since voting began.
Even though — or perhaps because — he has been favored all along to win the South Carolina primary, Mr. Biden drew virtually no attacks from other candidates in the run-up to Saturday’s vote.
In South Carolina, Mr. Biden wielded two powerful assets: longstanding relationships and a direct connection to Mr. Obama, who is beloved by black voters.
Mr. Biden was also aided immensely by his close bond with Representative James E. Clyburn, the highest-ranking African-American in Congress and the most influential Democrat in South Carolina.
After months of remaining neutral, Mr. Clyburn offered Mr. Biden a full-throated endorsement on Wednesday before a bank of television cameras and photographers. On Saturday, nearly 50 percent of South Carolina voters said Mr. Clyburn’s support was an important factor in their decision, according to exit polls.
Even more crucial to Mr. Biden was his service under the nation’s first black president, a relationship that earned him a reservoir of good will in a state where 56 percent of the Democratic electorate on Saturday was African-American, according to exit polls.
“He was Obama’s vice president and he stuck by him,” said Luther Johnson, a Columbia resident who came to see Mr. Biden at a black-owned barbershop on Friday.
Mr. Biden was noticeably more at ease as he wound his way through South Carolina’s churches, barbershops and barbecue joints than he had been in Iowa and New Hampshire. As he likes to remind people here, he has vacationed in the state’s Lowcountry for decades and, as a young senator mourning the death of his first wife, forged a close friendship with Ernest F. Hollings, South Carolina’s long-serving senator.
But Mr. Biden did not last long enough in his first two presidential campaigns to make it to South Carolina — Saturday marked his first win there, and his first primary victory anywhere, in his three White House bids.
South Carolina is the second consecutive diverse nominating state in which the share of white voters casting ballots was higher this year than it had been in the 2016 primaries — the latest evidence that President Trump has nudged some Republicans and independents into the Democratic column.
More people in South Carolina voted in this primary than in any other in its history, breaking the record set in the 2008 nominating contest.
Mr. Biden’s back-against-the-wall victory was in keeping with South Carolina’s tradition of turning around presidential campaigns. George W. Bush in 2000, Mr. Obama in 2008 and Hillary Clinton in 2016 all revived their candidacies in the state after losing decisively in New Hampshire.
Mr. Biden’s win on Saturday is no guarantee he will be catapulted to the nomination in the same fashion. Even as voters were going to the polls on Saturday, Mr. Clyburn offered a blistering assessment of Mr. Biden’s organization.
“We will have to sit down and get serious about how we retool this campaign,” the lawmaker said on CNN, adding: “I’m not going to sit back idly and watch people mishandle this campaign.”
Mr. Biden’s operations have been sorely lacking in Super Tuesday states, local Democrats say. Mr. Sanders is poised to rack up hundreds of delegates that day, including in large states like California, and Mr. Bloomberg and Ms. Warren are also in contention to claim delegates.
Mr. Buttigieg is also hoping to be competitive, but on a conference call on Saturday his campaign aides declined to say how many delegates he would need to win to remain viable.
“We really believe this is about limiting Senator Sanders’s lead and making sure that it is possible for an opposing candidate to close the gap in the remaining states that become more friendly,” said Michael Halle, a senior adviser to Mr. Buttigieg.
And in a sign that Mr. Bloomberg had no intention of yielding to a potential Biden comeback, his campaign announced on Saturday that it had purchased a lengthy block of airtime on multiple national networks for a three-minute commercial on Sunday, styled as an address by Mr. Bloomberg to the American people about the looming threat of the coronavirus.
Mr. Bloomberg’s campaign manager, Kevin Sheekey, responded to the South Carolina primary with a statement stressing that the candidate had not yet appeared on any primary ballot, and nodding toward the national scope of the primary on Tuesday.
“Mike is the only candidate to campaign in all fourteen Super Tuesday states over the last two months and we look forward to Tuesday,” Mr. Sheekey said.