Joe Biden rolled to commanding victories in pivotal Michigan and two other states on Tuesday, taking a big step toward the Democratic Party’s presidential nomination and dealing a stinging blow to rival Bernie Sanders’ fading White House bid.

Biden, the former vice president under Barack Obama, won over voters of all types to easily capture Missouri and Mississippi on a day when six states made their choices in the race to pick a challenger to Republican President Donald Trump.

The sweeping wins on Tuesday put Biden, 77, on a path to the nomination to face Trump in the November 3 election, while narrowing the path for Sanders, 78, who had hoped for an upset win in Michigan to keep his White House hopes alive.

Sanders’ loss in a state he won in the 2016 Democratic primary will increase pressure on the democratic socialist US senator from Vermont to exit the race and help Democrats prepare for a bruising election campaign against Trump.

Voters across the states that voted on Tuesday said they trusted Biden more to handle a major crisis by roughly 2-to-1 over Sanders, exit polls by Edison Research showed, a possible sign the fast-spreading coronavirus outbreak helped increase Biden’s appeal as a steady and experienced hand.

Speaking in Philadelphia, Biden thanked Sanders and his supporters for their energy and passion and appealed for party unity.

“We share a common goal and together we are going to defeat Donald Trump,” said Biden, who also mentioned his former rivals such as Pete Buttigieg, Amy Klobuchar and Kamala Harris who endorsed him after dropping their own presidential bids.

“Winning means uniting America. Not sowing more division and anger,” Biden said.

Sanders, who returned home to Vermont on Tuesday night, did not plan a public statement, a departure from his usual practice on primary nights.

With 83 per cent of precincts reporting, Biden led in Michigan with 53pc of the vote to 38pc for Sanders. Edison Research projected the primary turnout of 1.7 million would surpass the 1.2 million who voted in 2016.

In Washington state, Biden and Sanders were in a virtual tie with more than two-thirds of the votes counted.

Michigan was the biggest and most competitive of the six states that held nominating contests on Tuesday, which also included North Dakota and Idaho. It also is a crucial battleground that Trump narrowly and unexpectedly won in 2016, which along with wins in Pennsylvania and Wisconsin propelled his ascent to the White House.

The Biden breakthrough in Michigan, along with his dominant victories in Missouri and Mississippi, could be too much for Sanders to overcome, with the contest shifting to large states including Florida, Ohio and Georgia where Biden is seen as a clear favourite.

By the end of March, about two-thirds of the nearly 4,000 delegates to July’s Democratic nominating convention will be allocated.

So far on Tuesday, Biden had won 103 delegates to Sanders’ 48, giving him an overall lead of 731-593 in the race for the 1,991 delegates needed for the nomination, according to Edison Research.

“The math says Joe is our prohibitive nominee. We need to bring the party together,” former presidential candidate Andrew Yang said on CNN as he endorsed Biden.

One of Sanders’ most influential supporters, liberal US Representative Alexandria Ocasio-Cortez, acknowledged the depth of his defeat.

“There’s no sugar coating it,” she said on Instagram. “Tonight’s a tough night.”

Both candidates called off planned rallies in Cleveland on Tuesday because of concerns over the coronavirus outbreak, which has rattled markets and prompted Democrats to criticise the Trump administration’s response.

Winning Coalition

Biden was powered to victory on Tuesday by strong support from a broad coalition of groups, including women, African Americans, those aged 45 and older, union members and all but the very liberal, according to exit polls.

In Michigan, he performed well with union members and working-class white voters — two groups that helped Sanders to an upset victory over Hillary Clinton in the state in 2016 but did not turn out as strongly for him this time despite Sanders’ economic populism and his call for universal healthcare.

Sanders won large majorities of voters under 30 years old in Michigan, Missouri and Mississippi, yet that group had a smaller impact on the results this year. Voters between 18 and 29 made up 12pc of the Democratic primary electorate in Missouri, 10pc in Mississippi and 15pc in Michigan, down at least 4 percentage points in each state from 2016.

Biden, who had touted the Obama administration’s decision to bail out the state’s dominant auto industry, made a morning campaign stop on Tuesday at Detroit’s first new auto assembly plant in decades, owned by Fiat Chrysler Automobiles NV.

“Unions built the country,” Biden shouted through a bullhorn. “You’re the best damn workers in the world.”

Sanders had attacked Biden for his support for international trade deals like the 1994 North American Free Trade Agreement, which is unpopular in Michigan where workers say it cost the state jobs. But the argument appeared to make little headway in a party that seemed to have made up its mind about Biden.

By Tuesday night, there was a growing sense of inevitability surrounding Biden’s candidacy.

Two of the largest Democratic Super PACS said they were going to begin working for Biden. American Bridge President Bradley Beychok announced the group planned a $2.2 million ad buy in Pennsylvania for Biden.

“The math is now clear. Joe Biden is going to be the Democratic nominee,” Priorities USA Chairman Guy Cecil said on Twitter, adding the group would “do everything we can to help him defeat Donald Trump.”