Pete Buttigieg has ended his bid for the Democratic presidential nomination.

The former South Bend, Indiana, mayor confirmed on Sunday evening that he had suspended his campaign, a day after finishing a distant fourth in the South Carolina primary and two days before 14 states vote on Super Tuesday.

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Biden wins big in South Carolina

Buttigieg, the non-revolutionary Democrat

The contest in South Carolina was decisively won by Joe Biden, the former vice president who moderate candidates like Buttigieg may now rally behind in an attempt to stop Bernie Sanders topping the Democratic ticket in November's U.S. elections. 

"I am making the difficult decision to suspend my campaign for the presidency," Buttigieg told supporters in South Bend on Sunday evening.

"I will no longer seek to be the 2020 nominee for president, but I will do everything in my power to make sure we have a new Democratic president come January."

Buttigieg, a 38-year-old Afghan war veteran and first openly gay contender for a major party nomination, was the surprise package of the race.

A virtual unknown on the national stage when the campaign began, he vaulted into the top tier of candidates and hauled in impressive levels of fundraising, before winning the most delegates in the Iowa caucuses and finishing a close second to Bernie Sanders in New Hampshire.

The impact of his strong early performances were blunted by the chaotic reporting of results from Iowa and an impressive comeback from Amy Klobuchar in New Hampshire that saw her campaign gain a fundraising and media boost.

A lack of appeal to non-white voters was always expected to be a problem for Buttigieg, and in Nevada and South Carolina Buttigieg's momentum was stopped as he dropped to third- and fourth-place finishes respectively.

Polling from Super Tuesday states, where centrist billionaire Michael Bloomberg has spent hundreds of millions of U.S. dollars, suggested he would have struggled to win the 15 percent needed to win state delegates in most contests.

Buttigieg has not endorsed another candidate, but the decision to pull out is likely to be a major boost to Biden and could also help Bloomberg, Elizabeth Warren and Klobuchar, all of whom are more likely to pick up support from former Buttigieg supporters than Sanders.

Former President Barack Obama told Biden he will not endorse anyone, CNN reported on Sunday, during a phone call congratulating the 77-year-old on his victory in South Carolina. 

Sanders, the Vermont senator and delegate frontrunner, is expected to make major gains in delegate-rich states like California on Tuesday. He has been boosted by a surge in fundraising, taking 46.5 million U.S dollars in February.

Biden's campaign took in 5 million U.S. dollars the day of the South Carolina primary and raised a total of 18 million U.S. dollars in February.

Warren, who on Saturday vowed to stay in the race until the Democratic convention despite another poor finish, raised 29 million U.S. dollars in February.