Joe Biden, buoyed by a strong debate showing, received the endorsement of an influential black lawmaker on Wednesday, boosting his hopes of winning the South Carolina primary in what may be his last chance to derail Bernie Sanders' drive to the Democratic presidential nomination.

Jim Clyburn, the third-ranking Democrat in the House of Representatives, announced at an event in North Charleston, South Carolina, that he was endorsing the White House bid of the 77-year-old former vice president.

Democratic presidential hopeful Vermont Senator Bernie Sanders is on a roll Democratic presidential hopeful Vermont Senator Bernie Sanders is on a roll Photo: AFP / Paul Ratje

"South Carolina should be voting for Joe Biden," Clyburn said. "It is time for us to restore this country's dignity, this country's respect. And I can think of no one better suited, better prepared."

The endorsement of the popular South Carolina congressman carries considerable weight in the southern state, where black voters make up a majority of the Democratic electorate.

Former vice president Joe Biden will be hoping to bounce back from his dismal performance in Iowa and New Hampshire, where he finished fourth and fifth respectively Former vice president Joe Biden will be hoping to bounce back from his dismal performance in Iowa and New Hampshire, where he finished fourth and fifth respectively Photo: AFP / JIM WATSON

South Carolina holds its primary on Saturday, the last major test before "Super Tuesday" on March 3, when 14 states go to the polls and a whopping one-third of all delegates who pick the nominee at the party's July convention are up for grabs.

Biden, who served as vice president for eight years to America's first black president, Barack Obama, is counting on strong support among African-American voters in South Carolina to recharge his flagging campaign.

"Joe will build on President Obama's legacy," Clyburn said.

Pete Buttigieg has argued Bernie Sanders is too far to the left for many Americans and would be a weak opponent against President Donald Trump in November Pete Buttigieg has argued Bernie Sanders is too far to the left for many Americans and would be a weak opponent against President Donald Trump in November Photo: AFP / Jason Connolly

Biden was considered the front-runner after jumping into the race but he came in fourth in Iowa, fifth in New Hampshire and a distant second to Vermont Senator Sanders in Nevada.

The 78-year-old Sanders, a self-described "democratic socialist," finished in a virtual tie with former South Bend, Indiana, mayor Pete Buttigieg in Iowa and then went on to win in New Hampshire and Nevada.

Mike Bloomberg will be looking to rebound from his disastrous performance in his first debate and prove he is a credible, moderate alternative to the leftist Sanders Mike Bloomberg will be looking to rebound from his disastrous performance in his first debate and prove he is a credible, moderate alternative to the leftist Sanders Photo: AFP / Mark RALSTON

A strong performance in South Carolina could potentially allow Sanders to deliver a knockout blow to his rivals on Super Tuesday and all-but lock up the top spot on the Democratic ticket against Republican Donald Trump in November.

Democratic presidential hopeful Vermont Senator Bernie Sanders is in pole position heading into South Carolina's Democratic primary Democratic presidential hopeful Vermont Senator Bernie Sanders is in pole position heading into South Carolina's Democratic primary Photo: AFP / Jason Connolly

Biden is leading in the polls in South Carolina but Sanders has cut the deficit to single digits in some surveys.

Billionaire activist Tom Steyer has pumped millions of dollars into ads in South Carolina and is projected to finish third in the state.

Democratic presidential candidate Elizabeth Warren is reflected in a student's glasses as she speaks at South Carolina State University Democratic presidential candidate Elizabeth Warren is reflected in a student's glasses as she speaks at South Carolina State University Photo: GETTY IMAGES / SPENCER PLATT

Another billionaire, Michael Bloomberg, the former mayor of New York, is the only major candidate not on Saturday's ballot, having chosen to skip the four early voting states to make a splash on Super Tuesday.

Ahead of Saturday's vote, the candidates took part in a free-wheeling debate in Charleston on Tuesday night, aiming their fire at the front-runner Sanders and making appeals to black voters.

Steyer advocated reparations to African-Americans for slavery while Biden said that if elected he will put a black woman on the Supreme Court.

Biden accused Sanders of being soft on gun control while Bloomberg claimed Russia wanted the Vermont senator to win the nomination -- betting he would be defeated by Trump in November.

All of his rivals ganged up in describing Sanders as too radical to appeal to a broad swathe of Americans.

Fellow progressive Elizabeth Warren and centrists Buttigieg and Amy Klobuchar laid into his ability to deliver on costly programs such as universal health care and tuition-free public college.

Buttigieg, a 38-year-old military veteran presenting himself as a unifier, warned a Sanders fight against Trump would spell "chaos" and divide the nation.

"I tell you what it adds up to," Buttigieg said. "It ends up as four more years of Donald Trump."

Sanders hit back at the charge his policies were too "radical," insisting such ideas "exist in countries all over the world," including the notion that health care is a human right.

Biden put in a spirited performance and snapped back at moderators who tried to cut him off, telling them: "I'm not going to be quiet anymore, OK?"

Like Buttigieg, Bloomberg sought to cast a Sanders nomination as a sure path to losing.

"I'm the one choice that makes some sense," said Bloomberg, touting his experience running America's largest city for 12 years.

The 78-year-old billionaire found himself under assault too, including by Warren, who called him "the riskiest candidate" on stage.

"I don't care how much money mayor Bloomberg has. The core of the Democratic Party will never trust him," the senator from Massachusetts said.