NORTH CHARLESTON, S.C. — Joe Biden, never one to stifle his emotions, stood behind a microphone here, his eyes welling. The nation's highest-ranking black congressman, Rep. James E. Clyburn, had just bestowed his coveted endorsement, and for once, the former vice president seemed to hear some unconditionally good news.

“I’m voting for Joe Biden, and South Carolinians should be voting for Joe Biden,” Clyburn (D-S.C.) said, referring to the state’s Saturday primary. “I know Joe. We know Joe. But most importantly, Joe knows us.”

Another thing Joe knows: This is a make-or-break moment in a political career that began 48 years ago, and has taken him to the heights and back down again. Biden has run three presidential campaigns and has yet to win a primary or caucus. In three contests this year, he has finished fourth, fifth and second. His hopes are poured into turning his campaign around by winning South Carolina and rocketing into the Super Tuesday contests next week.

In perhaps the last dramatic opportunity before Saturday’s voting, Tuesday night’s debate in Charleston, nothing seemed to challenge Biden’s grip on the state’s dominant black voters, and no other candidate made a pitch strong enough to overcome their own problems.

“South Carolina chooses presidents,” Biden said Wednesday morning. “You decided to launch Bill Clinton to the White House, and up to that time, it didn’t look like he was going very far — but you did. You launched my buddy Barack Obama to the White House. I firmly believe, once again on Saturday, you hold in your hands, in South Carolina, the power to choose the next president of the United States.”

Not everything is as upbeat as Clyburn’s announcement. Even as he holds a small lead in polls, Biden is being vastly outspent on television and radio ads here. While the Clyburn endorsement could prove influential, Biden also secured the top endorsements in Iowa, New Hampshire and Nevada, and that helped little. And there is no certainty that even a convincing win could translate to victory when 14 other states and American Samoa vote on Super Tuesday three days later.

Biden has laid little groundwork in the next states, forced to spend almost all of his time in South Carolina this week as other candidates scatter to the next set of states. Strapped for cash, he is only now starting to buy advertising in some Super Tuesday states — and is spending a fraction of what his rivals are.

That puts even more pressure on South Carolina to give Biden a bounce.

Rep. G.K Butterfield (D-N.C.), a Biden ally, was boisterous about his chances: “I believe we will win by double digits on Saturday.” Biden was only slightly less effusive.

“I promise you this: If you send me out of South Carolina with a victory, there will be no stopping us,” Biden said. “We will win the nomination. We will win the presidency. And, most importantly, we’ll eliminate the fear so many have in this country of a second term of Donald Trump.”

Biden has struggled for most of his campaign, which began in April. His rhetoric has been rambling, desultory and occasionally false. Over the past two weeks, he several times told a story about being arrested in South Africa while seeking to meet with Nelson Mandela and later being thanked by him for it. Neither incident appears to have occurred.

His fundraising has foundered, and he has often struggled during debates. He has faced an onslaught of criticism from President Trump, whose request that the Ukrainian president investigate Biden and his son Hunter led to Trump’s impeachment.

Yet the dynamics of the race have conspired to keep Biden in it, even if he’s not in the front-runner position where he once hoped to reside. Sen. Bernie Sanders (I-Vt.) has emerged as the most dominant force in the race, but the contest to become the clear alternative to him has been muddled.

Biden’s advisers and allies hope that South Carolina is the answer. Rep. David E. Price (D-N.C.) had sat on the sidelines and watched the primary contest unfold. But after growing concerned about the unsettled field, he endorsed Biden this week.

“It’s very fragmented. That’s the dilemma,” he said. “You have to ask yourself, ‘Who has a real possibility of emerging right now, somebody who has the potential to unify the party . . . not necessarily everyone’s first choice but who can pull us together?’ I think Biden is the answer to that.”

In North Carolina, as in many other Super Tuesday states, Biden was the clear leader in the polls up until about two weeks ago, when the impact of his early primary losses began to be felt. He was at 32 percent in the state’s RealClearPolitics average on the day of the New Hampshire primary; Sanders was at 16 percent. Now, Sanders has a narrow lead, with Biden and former New York mayor Mike Bloomberg knotted in second.

Biden supporters believe that if he becomes the alternative to Sanders, those to the right of Sanders will begin consolidating around the former vice president.

“The best outcome here, given where we are, would be for Biden to regroup and emerge from South Carolina and Super Tuesday with real solid votes,” Price said.

“I wish the campaign had a stronger field operation. But whatever they’ve got, they need to make the most of it,” he said, adding, “This isn’t the time to skimp on anything, including TV budgets.”

Fletcher Smith, a former South Carolina state legislator who has endorsed and advised the Biden campaign in the Palmetto State, watched the Clyburn endorsement and had one critique: Neither Biden nor Clyburn asked for money.

“The problem is going to be that he has to start raising money in order to compete on Super Tuesday,” Smith said. “They’re going to have to compete not only with Mayor Bloomberg, but also with Bernie Sanders’s war chest. If he doesn’t do it right, the momentum coming out of South Carolina can be blunted.”

Biden’s campaign on Wednesday said it is planning to make its first advertising buys in Super Tuesday states, but the amount is limited to a modest six figures across seven states. The ad — which features President Barack Obama giving him the Presidential Medal of Freedom — will air in Southern states with high levels of African American voters, including Alabama, Arkansas, Georgia, North Carolina, Tennessee, Texas, and Virginia.

Biden continues to be heavily outspent by his rivals, according to data from the firm Advertising Analytics. All other campaigns have made significant investments throughout the race and have much more planned in the coming days.

Over the next week in Super Tuesday states, Bloomberg is spending $35 million, while businessman Tom Steyer is spending $5.9 million and Sanders is spending $3.6 million.

Sen. Amy Klobuchar (D-Minn.) is at $1.1 million — with another $356,000 from a super PAC backing her — while Sen. Elizabeth Warren (D-Mass.) is spending $628,000, with another $307,000 from the super PAC supporting her. Former South Bend, Ind., mayor Pete Buttigieg is spending about $25,000, according to the data.

Biden also has been outspent in South Carolina; his campaign and the super PAC supporting him have spent $1.1 million during the primary. It’s the lowest of anyone except Sanders — who is at $879,000 — and several candidates have more than doubled his spending.

Smith said one of the reasons that Biden has been able to hold on is that he came to the contest with a history with black voters, dating to his time in the Senate and as Obama’s vice president.

“We don’t believe that any white person that’s a politician is going to be perfect on any issue that affects black people,” Smith said. “Biden was for civil rights when civil rights wasn’t cool. But he stood up for Barack Obama. He did everything that [Obama] asked of him.”

At a town hall in Georgetown, S.C., a 90-minute drive from Charleston, Biden aides took down the teleprompter — his usual accompaniment — before he walked into the room to a standing ovation. He glanced at his notes only sparingly at the beginning, then spent most of the town hall wandering across the roped-off speaking area trying to connect with the audience. Occasionally, he resurrected old laugh lines that had been culled out of his speech as he’s been more intentional about attacking his opponents. The attacks were still there, dipped in sarcasm.

He told the crowd, “God bless Bernie,” as he ripped into his Medicare-for-all plan.

“Anybody that tells you, ‘I’ve got a great plan, but you’re going to love it in ten years, man,’ ” he joked. “ ‘Ten years, it’s going to be done.’ It’ll take the first three years to maybe get it passed — he’s never going to get it passed.”

He made fun of Trump, telling one woman who questioned the president’s intelligence, “I don’t think he thinks too well.” He joked with a woman whose baby started babbling during his speech. “I’m used to it,” he told her. “He can do whatever he wants.”

And he spoke about getting emotional earlier in the day in North Charleston, as Clyburn endorsed him, reflecting on a man he’s known for most of his political career.

“It was a little emotional for me because I’ve known Jim Clyburn and I’ve known his wife for a long, long time, for forty years,” he said. “And I know you measure the support you get as a consequence of . . . the respect you have for the person supporting you.”

Michele Freeman, 66, of Pawleys Island, said she was a supporter of Sen. Kamala D. Harris (D-Calif.) until she dropped out. Then she switched to Biden.

“I’m hoping that by having a win in South Carolina that it eliminates some of the fears,” she said. “I hope it just gets rid of the constant hesitation about whether he can actually pull it off.”

She’s committed to the former vice president through Super Tuesday but has worries about how his candidacy will fare. It he stumbles, she has a backup plan: Bloomberg.