Joe Biden’s flailing presidential bid received a significant boost on Wednesday following the endorsement of a powerful South Carolina Democrat, hours after the former vice-president declared during a turbulent debate among the still-divided Democratic field that he would win the state.

South Carolina, which votes on Saturday, is the fourth early voting state and marks the first time in the election cycle that African American voters will form a majority of the electorate.

Biden, Barack Obama’s vice-president, still holds a narrow lead in a state regarded as pivotal to his fortunes, against frontrunner Bernie Sanders, according to recent polls. His campaign has long targeted the state even after disappointing results in the earlier votes in Iowa and New Hampshire this month.

As centrist Democrats scramble to veer the nomination away from Sanders, Biden is seeking a convincing victory in South Carolina to bring his campaign back on track ahead of the crucial Super Tuesday vote next week. A total of 16 states and territories will vote next Tuesday as Sanders looks set for a convincing victory in California and a tight race in Texas with Biden.

The Democratic candidates met for a bruising debate on Tuesday evening for the last time ahead of voting.

Sanders was targeted by most of his rivals over his record on gun control, his past comments on communist Cuba, and ambitious spending plans for universal healthcare provision.

The debate descended into loud bickering and cross-talk at many points, a sign of the friction within the party over the best way to defeat Donald Trump in the November election.

Trump himself weighed in with his own assessment of the debate on Wednesday morning, describing it as “crazy, chaotic” and expressing confidence he would beat any of the major candidates. “Just give me an opponent!” Trump tweeted.

Despite the president’s confidence, national polling indicates he still falls behind all the top-tier Democratic candidates on a variety of slim margins.

On Wednesday morning at an event in North Charleston, Biden received the endorsement of House Democrat Jim Clyburn, a major powerbroker in South Carolina Democratic politics and the most senior African American in the US House of Representatives.

“I can think of no one better suited, better prepared, I can think of no one with the integrity, no one more committed to the fundamental principles that make this country what it is than my good friend,” Clyburn said as he appeared with Biden.

Sharing the podium with Clyburn, Biden issued another less than subtle dig at Sanders, a self-declared democratic socialist.

“Today, people are talking about a revolution,” Biden said. “But what the country’s looking for are results. What they’re looking for is security. What they’re looking for is being able to sustain and maintain their dignity.”

At an event half a mile down the road, hosted by the national civil rights leader Al Sharpton, a number of the candidates sought to strike a more conciliatory tone after Tuesday’s debate left the field appearing so disharmonious.

As Sharpton introduced Sanders to the crowd of assembled members of his National Action Network civil rights group, he told them: “Whatever you decide to do on Saturday, do not go by those who try to use the socialist tag [against Sanders] …” reminding the assembled members that civil rights leaders including Martin Luther King were branded the same way. “It’s time for all of us to be treated fairly.”

Sharpton is another prominent voice in the African American community who has been courted by all the major candidates but has not yet endorsed anyone in the race.

Sanders used his address to recall his active participation in the civil rights movement and remind attendees of his support for Obama.

“I was proud to support Barack Obama in both of his campaigns,” the Vermont senator said.

While reticence remains within the Democratic establishment about the prospect of a Sanders nomination, some senior Democrats have signalled, in public at least, they would be supportive should he win.

“I think whoever our nominee is, we will enthusiastically embrace and we will win the White House, the Senate and the House,” the House speaker, Nancy Pelosi, told reporters on Wednesday.