Dearborn, Michigan - In a continuation of the Super Tuesday turnout, Democratic voters turned out in droves on Tuesday for primaries in six states aimed at clearing up the question of who will go up against President Donald Trump in November - game-changer Bernie Sanders or the status quo candidate, Joe Biden.

Ultimately, Democratic voters opted for Biden, raising the question of whether Sanders will suspend his campaign.

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While the exact delegate counts will take days to tally, Biden won the popular vote in Michigan, Missouri, Mississippi, and Idaho. Sanders won the caucuses in North Dakota, but Washington state was still undecided as of 11am Eastern time (3pm GMT) on Wednesday.

Exit polls indicated that a pattern established in earlier states continued on Tuesday, with younger voters and Muslims opting for Sanders and older voters, along with African Americans and suburbanites, turning out for Biden. Voters told pollsters that one of their primary motivations was finding a candidate who can defeat Trump in the general election.

Joe Biden won the popular vote in Michigan, Missouri, and Mississippi [ Matt Rourke/ AP Photo]

Michigan turnout

Battleground state Michigan, which Sanders barely won in his 2016 race against former Secretary of State Hillary Clinton, was the big prize of the evening, with 125 delegates at stake and turnout was so heavy that election officials were all but overwhelmed.

In the Sanders stronghold of Dearborn, a city with one of the largest concentrations of Muslims in the US, there were long lines at the city clerk's office as people waited to register to vote. Tuesday's was the first election in Michigan that allowed voters to register the same day and the clerk's office was not prepared for the volume.

Activist and Sanders supporter Linda Sarsour witnessed the chaos. None of the staff spoke Arabic, she said, and by mid-afternoon, the lines were so long that she saw about seven people leave without voting because they had to pick up their kids from school.

"A good problem we're having as a community is that the turnout in this particular area is higher than expected, at least according to the clerk's office," Sarsour said.

A total of 352 delegates were up for grabs in all six states on Tuesday. Before the vote, Biden led Sanders by 628-545 in pledged delegates. A total of 1,991 is needed for the nomination.

Sanders out?

Before Tuesday night's results, Sanders had scoffed at the notion that he would drop out of the race if Tuesday went poorly. During a visit to polling stations in Detroit on Tuesday, he said he is now battling the "Democratic establishment" and rejected the idea that Biden is more electable.

"In a general election, which candidate can generate the enthusiasm and the excitement and the voter turnout we need?" Sanders asked. "If you want to defeat Trump, which all Democrats do and the majority of independents do and some Republicans do, we are that campaign."

Sanders is in an urgent fight to turn things around as the primary calendar quickly shifts to other states - Florida, Ohio, Illinois, and Arizona on March 17 and Georgia on March 24 - that could favour Biden and narrow Sanders' path to the nomination. Biden could easily build an insurmountable delegate lead if he runs up the score in the upcoming contests.

Recent polling in Florida makes that state look like a looming disaster for Sanders, mainly because of his past defence of the late Cuban leader Fidel Castro, and he faces long odds in Ohio and Illinois given the results in Michigan. The wild card next week could be Arizona, where Sanders will be counting on strong Latino support, which lifted him to victory in California.

The union vote

Union members, a powerful part of the Democratic base in industrial Michigan, turned out strongly for Biden on Tuesday.

During the day, members of Unite Here, a hospitality union, were hunched over telephones in their Detroit headquarters in an effort to get their 7,000 members out to vote for the former vice president.

Alicia Weaver, a union organiser in Detroit, Michigan, calls members of the Unite Here hospitality union in a get-out-the-vote efforts on Tuesday. [Hilary Beaumont/Al Jazeera]

Alicia Weaver, an organiser for the union, had been at it for nearly a week straight. She said she has been dismayed by the lack of respect garnered by the office of the president since Trump took office and wants to change that in November.

"It's almost like a reality show," Weaver said. She said she sees Biden as someone who can unite the country again. "There's too much division, and we need to come back together for the common good for everybody," she said.

Biden enjoys such strong support among union members because of the Obama administration bailouts that saved the car industry from oblivion after the 2008-2009 financial crisis. Terrell George, a Unite Here local board member said his members have long memories of how he rescued them from the brink of disaster.

"Biden was there for us, he stood up for us," George said. "A lot of union members and my uncle, in particular, kept their jobs. So he was there for us way before we were there for him."

Members of Unite Here say they are now turning their attention to the November contest. Weaver remembers being so confident about Michigan going to Democrat Hillary Clinton in her race against Trump in 2016 that she travelled to Nevada to help get out the vote there.

"That was a nightmare," she says of 2016. "We lost Michigan. We should have stayed home. If we had stayed home and concentrated on our own state, we probably could have won."

Weaver says she will not make the same mistake this year.

Magic school bus

Back in Dearborn, David Lam from Trenton, New Jersey was doing what he could to give Sanders an edge in Michigan. Lam rolled up to a mosque in a yellow school bus with Bernie signs on the windows, volunteering to drive people to the city clerk's office to register to vote. One older gentleman boarded his bus.

David Lam (left) drove to Dearborn, Michigan from Trenton, New Jersey in order to help voters in that state vote for Bernie Sanders during Tuesday's primary. [Hilary Beaumont/Al Jazeera]

Lam started volunteering for Sanders in 2016. This year, he volunteered for Vermont senator in Iowa and New Hampshire. They were supposed to have an official Bernie bus in New Hampshire, but the campaign sent that funding to Iowa.

"I've always wanted a bus, because I wanted to turn my bus into a tiny home on wheels, so I was like, 'Guys why don't I get the bus early?' They were like, 'Dave, go for it.' I got the bus a day, two days later. A week after that, we were in New Hampshire."

He did not stop. He drove the bus to South Carolina, North Carolina, and now Michigan. Before Tuesday's results, he said he expects his last trip to be Ohio.

About 7pm local time (23:00 GMT), after waiting about an hour in line, the older gentleman who got on Lam's bus said he had voted. He walked out of the clerk's office with a smile.