Pete Buttigieg, the first openly gay US presidential candidate from a major party, on Sunday ended his campaign to be the Democratic nominee in the November election against Donald Trump, US media said.
The 38-year-old had risen rapidly from being a virtual unknown to becoming a national political figure, but he scored poorly in the latest primary in South Carolina, coming fourth with just eight per cent.
He was scheduled to address supporters later Sunday in South Bend, Indiana, where he was previously the mayor.
Mr Buttigieg took centre stage when securing a narrow victory in the Iowa caucuses and earned national attention for his unflustered and professional approach in an often bitter Democratic nomination race.
But his showing in South Carolina on Saturday confirmed polls suggesting he struggled to attract support among black voters - a key demographic.
Joe Biden's resounding victory in South Carolina has thrust him back into the race just days before voters go to the polls in 14 "Super Tuesday" states.
With 48 per cent of the vote in South Carolina, the former vice president more than doubled the 20 per cent won by national frontrunner Bernie Sanders, reviving Mr Biden's campaign and positioning him as the leftist senator's main rival.
Mr Trump responded rapidly on Twitter, claiming that the Democratic party leadership would act to halt Mr Sanders winning.
"Pete Buttigieg is OUT. All of his SuperTuesday votes will go to Sleepy Joe Biden. Great timing. This is the REAL beginning of the Dems taking Bernie out of play," Mr Trump wrote.
Pressure to drop out
South Carolina brought some clarity: billionaire businessman Tom Steyer, who spent $23 million campaigning in the state, also dropped out of the race after taking just 11 per cent of the vote.
The pressure is mounting on other trailing Democrats - including Senator Elizabeth Warren and Senator Amy Klobuchar - to follow Mr Steyer's and Mr Buttigieg's example and then swiftly throw their weight behind a frontrunner.
Senator Elizabeth Warren and Senator Amy Klobuchar and billionaire Michael Bloomberg have all made it clear that they will stick around at least through Super Tuesday.
Mr Buttigieg was feted by rivals including Mr Bloomberg, another moderate, who has poured a staggering $500 million from his personal fortune into campaign advertising.
Mr Buttigieg "ran a strong campaign that inspired audiences and made history," Mr Bloomberg said.
Mr Biden praised Buttigieg for his "trail-blazing campaign based on courage, compassion, and honesty."
Many Mr Buttigieg supporters are unlikely to shift their backing to Bloomberg, whom Buttigieg openly accused of trying to "buy" his way into the presidential race.
The money factor
As the race goes forward, the money will loom ever larger.
Mr Biden claimed he had been outspent 40-to-1 in South Carolina, but said he raised $10 million over the weekend.
Mr Sanders has raised huge amounts in mostly small donations, including $46 million in February alone.
Mr Biden argued on Sunday that as a centrist, he would be far more effective atop the party's ticket in November against Trump than Sanders, who calls himself a democratic socialist.
"Most Americans don't want a promise of a revolution. What they want is results," he said in Virginia.
Mr Biden campaigns on Monday in Texas, Super Tuesday's second largest haul of the delegates who formally pick the party's nominee in July, while Sanders campaigns in Utah and in Klobuchar's home state of Minnesota.
