Former Vice President Joe Biden scored another batch of impressive primary victories on Tuesday, adding to his delegate lead and taking one more step ― maybe his final one ― toward the Democratic presidential nomination.

Biden won by a landslide in Mississippi, Missouri, and Michigan, putting on another commanding performance after his decisive wins in last week’s Super Tuesday contests. He also won in Idaho.

A coalition of diverse voters swung heavily in his favor over Sen. Bernie Sanders of Vermont, who won the North Dakota primary this week. Sanders’ campaign struggled to make up the difference with younger Americans and now faces a critical decision whether to continue his campaign.

“I want to thank Bernie Sanders and his supporters for their tireless passion. We share a common goal and together we’ll defeat Donald Trump,” Biden said at an event in Philadelphia, attempting a subtle pivot to the general election.

Biden is also expected to build on his delegate haul in Washington state.

At a campaign appearance in Detroit on Monday, Biden projected party unity by rallying with Sens. Kamala Harris of California and Cory Booker of New Jersey, two former rivals for the Democratic nomination who endorsed Biden over the weekend, as well as Michigan Gov. Gretchen Whitmer.

“It takes coalitions to win. And this campaign looks like this country and it looks like this city,” Whitmer said at the event, pointing to the diversity of the crowd.

JEFF KOWALSKY via Getty Images Rivals no more.

Black voters played a huge role in resuscitating Biden’s campaign, which struggled early last month after disappointing finishes in Iowa and New Hampshire. The trend continued on Tuesday: Biden won 84% of Black voters in Mississippi compared to Sanders’ 13%, per an early exit poll released by CNN.

Michigan, in particular, was seen as a pivotal state for Sanders’ campaign. A surprise win there could have at least reversed the narrative that the race was functionally over, even if Sanders had committed to staying in until the Democratic convention. The Vermont senator upset Hillary Clinton in the Great Lakes State in the 2016 Democratic primary, so he was a known commodity there. He focused heavily on the state in the past week, holding several huge rallies in Detroit and the college town of Ann Arbor.

But Sanders was no match for Biden in Michigan’s suburban and rural areas, particularly with white working-class workers there who also backed the former vice president in other primaries across the country.

Tuesday’s results prompted high-profile calls for Sanders to exit the race from top Democrats like House Majority Whip Jim Clyburn (D-S.C.), whose endorsement for Biden helped him win South Carolina’s primary last month:

Rep. Clyburn on NPR just now: "I think when the night is over, Joe Biden will be the prohibitive favorite to win the Democratic nomination... If the night ends the way it has begun" it's time to "shut this primary down," meaning the DNC should "step in" and cancel future debates. — Miles Parks (@MilesParks) March 11, 2020

Three top Democratic groups ― Priorities USA, American Bridge, and the Democratic Senatorial Campaign Committee ― also called Biden the presumptive nominee, upping pressure on Sanders to drop out of the race.

The map looks even more daunting for Sanders later this month when voters in Arizona, Florida, Illinois, Ohio (on March 17) and then Georgia (on March 24) head to the polls. Many of the same dynamics apply in these states. In Florida, for example, where 219 pledged delegates are up for grabs, Biden leads Sanders 61% to 12%, according to a recent poll.

Tuesday’s elections were overshadowed somewhat by the growing coronavirus outbreak. Both presidential candidates canceled their scheduled events in Ohio earlier in the day after state officials warned people about congregating in large events. Biden addressed the election results and the outbreak from Pennsylvania. Sanders, meanwhile, flew home to his home state of Vermont with no public remarks on Tuesday ― an unusual move that will fuel speculation about his exit from the race.

“There’s no sugar-coating it. Tonight’s a tough night. Tonight’s a tough night electorally,” Rep. Alexandria Ocasio-Cortez (D-N.Y.), Sanders’s top endorser, said in a live-chat on her Instagram page.

This story was updated with remarks from Biden and Rep. Alexandria Ocasio-Cortez.