Joe Biden was projected to win Saturday’s South Carolina Democratic primary by a huge margin, at least temporarily halting the momentum of Vermont Sen. Bernie Sanders and giving the former vice president’s campaign a jolt of life just three days before Super Tuesday.

“For all of you who have been knocked down, counted out, left behind — this is your campaign,” Biden told supporters in a victory speech in Columbia. “Just days ago the press and the pundits declared this candidacy dead. Now, thanks to you, the heart of the Democratic party, we just won and we’ve just won big because of you and we are very much alive.”

With 81 percent of the vote counted, Biden had nearly 50 percent of the vote to 19 percent for Sanders.

Tom Steyer, a billionaire who had plowed millions of dollars in advertising into the state with a focus on racial justice and climate issues, looked headed for a third-place finish with 11 percent. Steyer announced Saturday night that his campaign is over.

“Honestly, I can’t see a path where I can win the presidency,” Steyer said.

Edison Research exit polls show Biden’s South Carolina support cutting across a wide range of voters, while Sanders’s support was limited to those under the age of 29.

“If Democrats want to nominate someone who will build on Obamacare, not scrap it, take on the NRA and gun manufacturers, not protect them, stand up and give the poor a fighting chance and the middle class get restored, not raise their taxes and keep the promises we make, then join us,” Biden declared. “And if the Democrats want a nominee who’s a Democrat, a lifelong Democrat, a proud Democrat, an Obama-Biden Democrat, then join us.”

Biden led all candidates among African Americans, those who oppose a single government health plan, those who faithfully attend religious services, people age 45 and older, the military, those who are somewhat liberal and very liberal, and voters who made up their minds in recent days.

A CNN exit poll showed Biden winning the black vote overwhelmingly, with 60 percent going for him well ahead of Sanders, who had 17 percent.

Sanders told supporters in Virginia Beach that winning in every state was not possible.

“Tonight we did not win in South Carolina, and this will not be our only defeat,” he said to supporters, who responded with boos. “There are a lot of states in this country and nobody wins them all.”

For Biden, who began his day at a polling place in Greenville, Saturday’s South Carolina primary was seen as nearly a make-or-break contest, with the season’s first large pool of black voters counted on to get him into the winner’s column.

Biden tweeted his thanks shortly after the projections were called.

Biden’s trajectory got a big boost Wednesday with an endorsement from House Majority Whip James Clyburn, one of the most influential Democrats in the state and the highest ranking African American in Congress.

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“I want the public to know I am voting for Joe Biden,” Clyburn said Wednesday. “South Carolina should be voting for Joe Biden.”

He backed the endorsement with a pledge to mobilize his organizing apparatus for Biden and echoed his choice on social media.

“I know Joe Biden. I know his character, his heart, and his record. Joe Biden has stood for the hard-working people of South Carolina,” Clyburn tweeted. “We know Joe. But more importantly, he knows us. In South Carolina, we choose presidents. I’m calling on you to stand with @JoeBiden.”

Exit polls conducted by Edison Research show Clyburn’s endorsement influenced about half of those who intended to vote Saturday, reports The Washington Post.

In his victory speech, Biden acknowledged Clyburn’s influence.

“My buddy Jim Clyburn, you brought me back.”

South Carolina’s support is especially important because Biden has struggled to raise money heading into Super Tuesday on March 3, when about one-third of the total delegates needed for nomination will be at stake in 14 states and two other jurisdictions.

“What I’m expecting is to make the case to people here in South Carolina that they have an opportunity to essentially determine who the next president is,” Biden told reporters in Charleston in the days leading to the vote. “Whomever wins this primary is going to go into Super Tuesday very strongly. And I think it’s going to be Bernie and me going into Super Tuesday.”

The urgency of the primary was illustrated in vivid terms Tuesday in Charleston during the Democratic debate, a raucous affair in which Biden had what was widely viewed as one of his strongest performances.

In polling as of Thursday, Biden was up 15 points in a RealClearPolitics.com average of several polls, but individually the margins have varied greatly.

South Carolina voting followed the Nevada caucuses a week earlier, when Vermont Sen. Bernie Sanders steamrolled the field. But Biden managed to capture second place, bettering his showing in the Iowa Caucuses and in New Hampshire.

Sanders appeared to be looking ahead to Tuesday’s vote.

He spent part of the past week between North Carolina, Virginia and South Carolina, and planned to be in Virginia for two rallies Saturday night.

The South Carolina primary is an open primary, with the state awarding 63 delegates, of which 54 are pledged and allocated based on the results of the primary.

Those candidates in the field running against Sanders have argued since he gained front-runner status that his nomination would threaten the party’s chances at the White House and even pull down Democrats running for other offices in November.

“I do believe that it would be problematic with Bernie Sanders and his so-called democratic socialist label,” Clyburn said in an interview with The Post and Courier this week. “A lot of people, not just in South Carolina, but in this part of the country would have a problem with that label.”

The potential complication for Biden in South Carolina was Steyer but his votes were far less than he had hoped his money and message would buy.

Among the other candidates, Sen. Amy Klobuchar of Minnesota was largely absent in the state. Mike Bloomberg, the billionaire former mayor of New York City, was not on the ballot.

Even before news of Biden’s win was declared, Bloomberg announced his own plan to deliver a three-minute prime-time address Sunday night on two television networks. He didn’t say how much he paid for the air time, which is unprecedented in recent decades.

Former South Bend, Indiana, Mayor Pete Buttigieg and Sen. Elizabeth Warren of Massachusetts were polling low and working to pick up the 15 percent of support required to pick up at least some delegates.

Their efforts, though, were mostly directed at Tuesday’s voting.

Super Tuesday is voting day for Alabama, American Samoa, Arkansas, California, Colorado, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, Utah, Vermont, Virginia Democratic and Democrats Abroad.

The South Carolina vote took place after a group of upstate Republicans urged conservatives to vote for Sanders in the state’s primary. A flier promoting their cause — “Operation Chaos” — was distributed at the president’s Friday night rally in North Charleston, The Washington Post reported Saturday.

Trav Robertson, the chairman of South Carolina’s Democratic Party, said that the plan would not work.

“People can rationalize any action and consequence thereof,” Robertson told the Post. “You’ve got a situation where the Republicans have an anti-Christian, amoral president and they have to rationalize an extremely high Democratic turnout and moderate Republicans voting for what they see as moderate Democrats.”

Going into Saturday, Sanders led in the delegate count with 46, followed by Buttigieg, 25; Biden, 15; Warren, 8; ad Klobuchar, 7.

The Associated Press contributed to this report.