Former US vice-president Joe Biden extended his lead over Senator Bernie Sanders, winning four of the six states that held their Democratic presidential nominating contests on Tuesday, including the prize catch of the evening, Michigan.

Biden also picked up Mississippi, Missouri and Idaho, continuing his winning spree from the South Carolina primaries.

He had gone on to win 10 of the 14 states that polled in the Super Tuesday contests last week in a stunning reversal of fortunes, resurrecting his campaign against all odds.

Washington state and North Dakota, the other two battlegrounds that went to polls this Tuesday, are still counting their votes; and Sanders is projected to take North Dakota.

Biden struck a conciliatory tone in his victory speech in Philadelphia. “I want to thank Bernie Sanders and his supporters for their tireless passion,” he said, with his wife Jill Biden by his side. “We share a common goal and together we’ll defeat (US President) Donald Trump.”

The results of the Super Tuesday II contests may not have sealed the race yet for Biden, but they certainly made Sanders’ path to the nomination highly improbable because of the widening gap between him and the former vice-president in terms of the tally of delegates required to reach the finishing line of 1,991. Biden currently leads Sanders 724-591.

Sanders had won four of these six states in the 2016 primaries against Hillary Clinton, including Michigan. And his chances look bleak in the next four states that hold their nominating contests next Tuesday that are likely to put Biden even further out his reach.