Joe Biden decisively won the key battleground state of Michigan and at least three others on Tuesday, further extending his lead over Bernie Sanders in the Democratic presidential primary.
The former Vice-President also took Missouri, Mississippi and Idaho, giving him a near-unassailable advantage in the race to choose who will face Donald Trump in November.
Biden again showed strength with working-class voters and African Americans, who are vital to winning the Democratic nomination.
Sanders' narrow hopes now rest on North Dakota and Washington state.
Addressing supporters in Philadelphia, Biden noted that many had “declared that this candidacy was dead” only days ago, but “now we're very much alive.”
He also asked Sanders supporters to switch and get behind him.
“We need you, we want you, and there’s a place in our campaign for each of you. I want to thank Bernie Sanders and his supporters for their tireless energy and their passion,” Biden said. "We share a common goal, and together we’ll beat Donald Trump.”
Guy Cecil, chairman of the flagship Democratic outside political organization Priorities USA, tweeted: “The math is now clear. Joe Biden is going to be the Democratic nominee for President and @prioritiesUSA is going to do everything we can to help him defeat Donald Trump in November.”
One of the few bright notes for Sanders was his strength among young voters, but even that has a downside because they didn't turn out enough to keep him competitive. Sanders won 72% of those under 30 in Missouri and 65% in Michigan, according to AP VoteCast.
Sanders has vowed not to drop out regardless of Tuesday's results and frequently railed against the “Democratic establishment” that he says has aligned against him.