Former vice president Joe Biden notched up a resounding win in the South Carolina primary on Saturday, reviving his campaign for the Democratic presidential nomination and positioning him as the leading rival to frontrunner Bernie Sanders.

The victory, powered by support from African-American voters, was the 77-year-old Biden's first in the race and may give him momentum going into "Super Tuesday" next week, when 14 states go to the polls.

Democratic White House hopeful Joe Biden believes a strong showing in South Carolina will propel him into national contention in the party's presidential nomination battle
Democratic White House hopeful Joe Biden believes a strong showing in South Carolina will propel him into national contention in the party's presidential nomination battle AFP / Jim WATSON

"Just days ago the press and the pundits had declared this candidacy dead," Biden told hundreds of supporters at a victory rally in the South Carolina capital Columbia.

"You've launched our campaign on the path to defeating Donald Trump," he said.

Democratic presidential hopeful Elizabeth Warren, a progressive senator from Massachusetts, is among several candidates who will be under pressure to end their campaigns if they fail to do well in the Super Tuesday voting
Democratic presidential hopeful Elizabeth Warren, a progressive senator from Massachusetts, is among several candidates who will be under pressure to end their campaigns if they fail to do well in the Super Tuesday voting AFP / Logan CYRUS

"We have the option of winning big or losing big," Biden added in a dig at Sanders' prospects against Trump in November's election.

With 99 percent of the ballots counted, Biden had 48.4 percent to 20 percent for the 78-year-old Senator Sanders, a self-described "democratic socialist."

Trump drew criticism for scheduling a rally in South Carolina with the coronavirus crisis deepening
Trump drew criticism for scheduling a rally in South Carolina with the coronavirus crisis deepening AFP / Nicholas Kamm

Billionaire activist Tom Steyer, who spent a whopping $23 million on advertising in South Carolina, was next with 11.4 percent but announced he was quitting the race even before the final results were published.

Former South Bend, Indiana mayor Pete Buttigieg, who has been challenging Biden for the centrist vote, had eight percent while Massachusetts Senator Elizabeth Warren had seven percent.

Bernie Sanders, frontrunner for the Democratic presidential nomination, has come under criticism from establishment Democrats for his liberal positions, which they feel will make him vulnerable to President Donald Trump in the November 2020 election
Bernie Sanders, frontrunner for the Democratic presidential nomination, has come under criticism from establishment Democrats for his liberal positions, which they feel will make him vulnerable to President Donald Trump in the November 2020 election AFP / JIM WATSON

A victory in South Carolina, where African-Americans make up around 60 percent of the Democratic primary electorate, was seen as crucial to Biden's hopes of reviving his flagging campaign.

Sanders has been the clear leader in the overall race, winning two of the first three contests and finishing in a virtual tie in Iowa with the 38-year-old Buttigieg.

South Carolina was seen as a key test of Sanders' support among African-Americans -- crucial to a Democratic victory in November -- but he only received the backing of around 15 percent of black voters while Biden received 60 percent according to exit polls.

Chart showing support for top candidates in the US Democratic presidential nomination race as of Nov 19, according to RealClearPolitics polling average.
Chart showing support for top candidates in the US Democratic presidential nomination race as of Nov 19, according to RealClearPolitics polling average. AFP / Gal ROMA
Democratic presidential hopeful Elizabeth Warren, a progressive senator from Massachusetts, is among several candidates who will be under pressure to end their campaigns if they fail to do well in the Super Tuesday voting
Democratic presidential hopeful Elizabeth Warren, a progressive senator from Massachusetts, is among several candidates who will be under pressure to end their campaigns if they fail to do well in the Super Tuesday voting AFP / JIM WATSON

Biden finished fourth in Iowa, fifth in New Hampshire and second in Nevada, and desperately needed a win in South Carolina ahead of Super Tuesday, which decides a third of the delegates who formally choose the Democratic nominee at the July party convention.

"The biggest question is whether this will slingshot Joe Biden into victory in some Super Tuesday states," said Larry Sabato, director of the Center for Politics at the University of Virginia.

Biden celebrates his South Carolina win
Biden celebrates his South Carolina win AFPTV / Gianrigo MARLETTA

Sabato said Biden's primary win -- his first in three attempts at securing the Democratic presidential nomination -- also increases the pressure on the other centrist candidates to leave the race.

Buttigieg, Warren, Minnesota Senator Amy Klobuchar and billionaire Michael Bloomberg have all made it clear they will stick around at least through Super Tuesday.

"Super Tuesday is three days away and we're looking forward to these big contests," Warren, who has been challenging Sanders for the progressive vote, told supporters at a campaign rally in Texas.

Sanders congratulated Biden on his victory at a campaign rally in Virginia but was confident of victory in the next primaries.

"The people on Super Tuesday and after are going to support this campaign," he said. "We are a movement of millions of people."

Sanders also dismissed Democratic establishment fears that he would lose against Trump, noting that dozens of polls have him beating the Republican incumbent.

Trump also praised Biden's victory and called on Bloomberg to quit the race.

"Sleepy Joe Biden's victory in the South Carolina Democrat Primary should be the end of Mini Mike Bloomberg's Joke of a campaign," the president tweeted.

The Bloomberg campaign, which has invested heavily in the Super Tuesday races, noted that the former New York mayor was not on the ballot in South Carolina.

Biden, who served for eight years as vice president to Barack Obama, was the favorite in South Carolina, the first state with a substantial African-American electorate to hold a primary contest.

"I can't wait for Super Tuesday to see him win all of those, every last one of those," Malone said.

Despite his South Carolina win, Biden may well face a Sanders buzzsaw on Super Tuesday.

Sanders, who narrowly lost the nomination to Hillary Clinton in 2016, is leading in nine of the 14 states to vote on Tuesday including California and Texas, the two biggest prizes.