Joe Biden has cemented his position as front-runner in the Democratic race to take on President Donald Trump in November's White House election.
The former vice-president is projected to win Michigan - the biggest prize of primary voting on Tuesday - and extend his lead over Bernie Sanders.
Mr Biden's chances had recovered with big wins on Super Tuesday after which several former rivals endorsed him.
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It is unclear if Mr Sanders will fight on until the party convention in July.
The Democrats' next big election milestone is in a week's time when 577 delegates are up for grabs.
To secure the nomination, a candidate needs the support of 1,991 delegates. Before Tuesday's vote, Mr Biden had 648 to Mr Sanders' 563.
What is Biden's message?
Joe Biden's campaign looked all but lost at the start of the primary season in February.
The former vice-president, 77, finished a poor fourth in the Iowa caucuses and fifth in the New Hampshire primary.
But the turn came with South Carolina - where he won due to the support of the large African-American community - and on the 3 March Super Tuesday he won 10 out of 14 states at stake, establishing a sizeable lead over the Vermont senator.
Thanking supporters from Philadelphia on Tuesday evening, Mr Biden said Democrats, including supporters of Bernie Sanders, could beat Donald Trump.
"It's more than a comeback, this campaign," he said. "It's comeback for the soul of this nation."
"Tonight we are a step closer to restoring dignity and honour to the White House," Mr Biden added.
"We have to lead the world again," the former vice-president said. "Donald Trump's America First policy has made America alone."
Senator Sanders, 78, enjoys widespread support among young voters, but has so far failed to turn that into electoral success.
