Former US Vice President Joe Biden moved a step closer to a November showdown with Donald Trump, notching up big primary wins over Bernie Sanders, his sole remaining major challenger for the Democratic presidential nomination.
Mr Biden, 77, the centre-left candidate, cruised to victory in Missouri, Mississippi and Idaho and scored a resounding win in Michigan, where Mr Sanders, 78, the self-described "democratic socialist" senator from Vermont, had hoped to make a stand.
The race was too close to call in Washington, the other major prize at stake, while North Dakota was still counting votes.
Former Vice President Joe Biden and Dr. Jill Biden take the stage to deliver remarks after wining the Michigan Primary Source: Bastiaan Slabbers/Sipa USA
Addressing supporters in Philadelphia as his victory took shape, Mr Biden struck a presidential tone as he declared on national television that he would lead "a comeback for the soul of this nation."
"We're bringing this party together," he said. "Tonight we're a step closer to restoring decency, dignity and honour to the White House."
Mr Biden reached out to his sometimes bitter rival Sanders and his supporters, telling them "we share a common goal."
"Together we'll defeat Donald Trump," he said.
Mr Biden's huge victory in Mississippi where he won around 80 per cent of the vote, reflected his popularity among strategically vital African-American voters. He defeated Mr Sanders by 25 points in Missouri.
His win in Michigan, the Midwestern industrial state which could be a key battleground in November, was a major setback for Mr Sanders, who narrowly beat Hillary Clinton there four years ago.
Barring surprises, Mr Biden now has a clear path to becoming the Democratic standard-bearer in a potentially bruising and deeply divisive matchup with the Republican incumbent Trump.
The main question remaining is whether Mr Sanders will fight to the bitter end as he did four years ago against Mrs Clinton or bow out early.
Many Democrats accuse the firebrand Sanders and his devoted supporters of damaging Mrs Clinton just as she was struggling - ultimately unsuccessfully - against the Trump insurgency.
'Tough night'
Mr Sanders did not immediately address Tuesday's results.
But his press secretary indicated he had no intention of pulling out, touting Sunday's next debate as the chance for America to "see Biden defend his ideas or lack thereof."
Alexandra Ocasio-Cortez, the charismatic New York congresswoman who is one of Mr Sanders' most high-profile supporters, said there was no "sugarcoating" the results, however.
Alexandria Ocasio-Cortez and Democratic presidential candidate Sen. Bernie Sanders stand together during his campaign event at Durham, New Hampshire. Source: Getty Images North America
"Tonight's a tough night for the movement," Ms Ocasio-Cortez said.
Adding to nerves in a country on edge after three tumultuous years under President Trump, fears of the coronavirus epidemic prompted both campaigns to cancel election-night rallies planned in Cleveland, Ohio.
Organisers of the upcoming television debate between Mr Sanders and Mr Biden likewise said they would take the extraordinary step of not allowing the usual live audience.
Their caution was at odds with Mr Trump, who has vowed to keep holding his typically raucous rallies despite the concerns about large gatherings.
Mr Trump's campaign manager dismissed Tuesday's results, saying "it has never mattered who the Democratic nominee turns out to be."
Both are "running on a big government socialist agenda" and Mr Trump "is on an unstoppable drive toward re-election," campaign manager Brad Parscale said.
For Mr Biden, Tuesday's six-state contest, coming a week after his strong Super Tuesday performance, demonstrated that his once shambolic campaign is gathering strength and is now ready to face Mr Trump.
A supporter holds a campaign sign as he waits at the entrance after a campaign rally of Democratic presidential candidate Bernie Sanders has been cancelled Source: Getty Images North America
Michigan in particular, which Trump narrowly won in 2016, was targeted by Mr Biden as a place to put down a marker ahead of the November election.
Mr Sanders had accused Mr Biden of selling out to corporate interests and ignoring a passionate leftist base.
But the former vice president has insisted on steering a centrist line that he says can bring the divided country back together - and it appears to have paid off.
'Traditional Democratic coalition'
Banking on his credibility as Obama's vice president, he has managed to get out an enthusiastic black vote.
With stories of a hard-knock childhood frequently featuring in his speeches, Mr Biden also wants to recapture the blue-collar white voters that Trump successfully poached from the Democrats in 2016.
"Biden is putting together the traditional Democratic coalition, and that's still a very powerful one," said Julian Zelizer, a professor of political history at Princeton University.
In another boost, Andrew Yang became the latest of a string of former rivals for the Democratic nomination to endorse Mr Biden.
As the candidate, however, Mr Biden will face an intensely polarized landscape, as illustrated during a campaign stop early Tuesday.
Mr Biden was speaking at an under-construction automobile plant in Detroit, Michigan, when he was confronted by a worker who accused him of planning to take away Americans' firearms.
In the startling exchange, Biden struck back, telling the worker he was "full of shit" and insisting that he supports the constitutional right to bear arms.
Democratic presidential candidate Joe Biden meets workers as he tours the Fiat Chrysler plant in Detroit Source: AFP
"I'm not taking your gun away," he said in the encounter, which Mr Trump backers pointed to as evidence of Biden's inability to stand pressure - but his own supporters saw as a show of mettle.
