The sweeping wins put the 77-year-old on a path to face Trump in the 3 November election,and the former vice president quickly looked ahead with a call for party unity and an appeal to supporters of Sanders.
“We share a common goal, and together we are going to defeat Donald Trump,” Biden said in Philadelphia, thanking Sanders and his supporters for their energy and passion.
His wins in the four states were powered by a broad coalition of supporters, including women, African Americans, those with and without college degrees, older voters, union members and all but the very liberal, according to exit polls by Edison Research.
Two other states, Washington and North Dakota, were still too close to call, but the results narrowed the path forward for Sanders, 78, who had hoped for an upset win in Michigan to keep his White House hopes alive.
The loss in a state Sanders won during his 2016 White House campaign will increase the pressure on the democratic socialist senator from Vermont to exit the race and help Democrats prepare for a bruising campaign against Trump.
With 91 per cent of the precincts reporting, Biden had 53 per cent of the vote in Michigan, well ahead of Sanders’ 37 per cent. He also won Missouri and Mississippi with 60 per cent and 81 per cent of the vote, respectively.
Sanders, who returned home to Vermont on Tuesday night, did not make a public statement after his losses, a departure from his usual practice on primary nights.
Voters across the states that voted on Tuesday said they trusted Biden more to handle a major crisis by roughly two-to-one over Sanders, exit polls showed, a possible sign the fast-spreading coronavirus outbreak helped increase Biden’s appeal as a steady and experienced hand.
Both candidates canceled planned rallies on Tuesday night in response to the outbreak, citing recommendations from public health officials to avoid assembling large indoor crowds.
Biden’s campaign also canceled a Thursday get-out-the-vote event in Florida, one of four states that will hold nominating contests next week. Biden said he would instead deliver an address on Thursday on the U.S. coronavirus response in his hometown of Wilmington, Delaware.
“This whole coronavirus is a matter of presidential leadership,” said Biden, the former vice president under Barack Obama.
Andrew Buncombe has this report.