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.