CHARLOTTE, N.C. — Is Bernie Sanders unstoppable? Did Joseph R. Biden Jr. gain enough lift from South Carolina to push aside Michael R. Bloomberg and Senator Elizabeth Warren and make it a two-person race?
Answers to both questions will be written across 14 states from coast to coast on Tuesday. And perhaps nowhere more than in North Carolina will the strength of a potential Biden revival and a reset of the Democratic primary be calibrated.
This state, which awards the third most delegates after California and Texas on Super Tuesday, is demographically suited to Mr. Biden: One in three Democrats here are African-American, and many college-educated suburbanites live in greater Charlotte and in the Raleigh-Durham region.
Together, the five Southern states apart from Texas that are voting — which carry about 25 percent of the total delegates to be won on Tuesday — will show whether Mr. Biden can continue sweeping up black voters, and whether he can coalesce enough moderates to deprive Mr. Sanders of a nearly insurmountable lead.
“Biden really got off of life support last night,” said Michael Bitzer, a political scientist at Catawba College in North Carolina, speaking the day after Mr. Biden’s landslide victory in South Carolina. “If he can at least be competitive on Tuesday in North Carolina, Virginia, Tennessee, Alabama and Arkansas, and be competing in Texas, he may have a good night.”
But there are plenty of obstacles to that rosy scenario: Nearly 800,000 people voted early in the state, before the South Carolina results or the twin endorsements of Mr. Biden on Monday by Pete Buttigieg and Amy Klobuchar, who ended their campaigns. Mr. Biden is a David against the Goliath of Mr. Bloomberg’s spending. And Mr. Sanders, who came relatively close to Hillary Clinton here in 2016, retains many supporters.
Bill Toole, a Democratic candidate for lieutenant governor, said Mr. Bloomberg “has a chance here” because of the state’s moderate leanings and because Mr. Biden had disappointed many Democrats with his uneven debate performances and early-state losses.
“People want to see a candidate who can win and who is moderate,” Mr. Toole said on Saturday before the full South Carolina results were reported, which showed Mr. Biden carrying black voters nearly four to one over Mr. Sanders. “If Biden had been more on his game, he would have been that person, but he’s faltered enough that people are uncertain.”
Mr. Toole was working the crowd in Charlotte at a state Democratic Party dinner where the keynote speaker was Mr. Bloomberg, the billionaire former mayor of New York City. The presence of Mr. Bloomberg, who said he had 124 paid staff members and 10 offices in North Carolina, is ubiquitous in TV ads, pitches to voters in the mail and online, and yard signs at seemingly every intersection. He has spent nearly $15 million in ads here, nine times as much as Mr. Sanders and 60 times as much as Mr. Biden, according to The Charlotte Observer.
When Mr. Bloomberg was asked after the dinner, once Mr. Biden’s commanding win in South Carolina was clear, whether he was a spoiler who could end up benefiting Mr. Sanders, he declined to answer.
A polling average of North Carolina, which does not include surveys taken after South Carolina’s results, shows Mr. Biden at 24.6 percent, just ahead of Mr. Sanders at 23.2 percent. Mr. Bloomberg was at 16.4 percent and Mr. Buttigieg, who withdrew from the race on Sunday, was in single digits. Though Mr. Buttigieg said he was dropping out in part so he would not split the anti-Sanders vote, and on Monday planned to throw his weight behind Mr. Biden, it is unclear where most of his backers will go. In polls they have named various second choices, including Ms. Warren.
Mr. Sanders has been courting black voters in North Carolina. He attended an Ash Wednesday service in Goldsboro at the church of the Rev. Dr. William J. Barber II, a former state N.A.A.C.P. president, and led a march to an early voting site from Winston-Salem State University, a historically black college.
Jillian Johnson, a co-chair of the Sanders campaign in the state, pointed to a 50 percent increase in early voting this year by millennials in Durham County, a stronghold of progressive politics. “If that trend holds, we will see Sanders getting an edge,” said Ms. Johnson, who is mayor pro tempore of the city of Durham. “Our turnout in Durham can flip an entire state election.”
She said she expected Mr. Sanders to do well, “but it’s not going to be Nevada,” where he beat Mr. Biden by more than 25 percentage points.
North Carolina had 17 days of early voting that ended on Saturday afternoon, before Mr. Biden’s victory in South Carolina. The total number of early votes surpassed those in the 2016 primary. In interviews, many Democrats said they were unusually conflicted and unsure who would be most likely to defeat President Trump, and so were hesitating to cast a ballot. A major uncertainty is how many waited for a sign from South Carolina, and whether there will be a surge of in-person turnout on Tuesday.
One South Carolina result that may haunt Mr. Bloomberg: the humiliating third-place finish there by another billionaire, Tom Steyer, who had spent lavishly to court black voters and dropped out after earning only 11 percent in the state.
“It could be the canary in the coal mine for Bloomberg,” Mr. Bitzer said. “Bloomberg’s strength tends to be among moderate suburban voters. But if Biden’s South Carolina victory kind of shifts them back over to his camp, Bloomberg may see a lot of his money go up the chimney Tuesday night.”
On Saturday, before the South Carolina polls had closed, Mr. Biden appeared at St. Augustine’s University, a historically black college in Raleigh, N.C. The crowd that filled a university gymnasium was modest compared with the multitudes who came out later that day in the same city to hear Mr. Buttigieg, one day before he withdrew.
But Mr. Biden seemed energized by the prospect of a good night in South Carolina, and his performance sent an electricity through the crowd that is not always seen at his rallies. He blended chestnuts from his biography with pointed attacks on the National Rifle Association and the “poisonous rhetoric” of Mr. Trump.
“I’ve lived through some moments of crisis in my life and my family, but I’ll be damned if I’m going to lose my country to this man,” he said, drawing loud applause.
“If North Carolina stays with us on Tuesday,” he predicted, “there’ll be no stopping us from there to the nomination.”
Mary Ann Parrott, who works for an education publisher, had entered the gym waffling among moderate candidates, worried that Mr. Biden’s performance in the debates suggested he was not forceful or focused enough to take on Mr. Trump.
She had a different view on the way out.
“Today he was everything I needed him to be,” she said.