DETROIT: Joe Biden took a vice-like grip on the Democratic nomination race Tuesday with big primary wins in Michigan and other states confirming his growing advantage over leftist Bernie Sanders in the contest to take on President Donald Trump.First US networks projected a huge victory in Mississippi for Biden, reflecting his popularity among strategically vital African American voters. Then came Missouri and, biggest of all, Michigan -- one of the industrial Midwestern giants due to be a key battleground in the general election."Thank you Michigan!" tweeted Biden, still waiting for results from three more states holding primaries before the night was over.Barring major surprises, Biden now eyes a strong path to becoming the Democrats' candidate in the bruising and deeply divisive November polls.But if the veteran centrist and former vice president under Barack Obama might increasingly shift focus on trying to make Trump a one-term president, Sanders' next step remains a big question.Will he fight on to the bitter end, as he did four years ago against the eventual nominee Hillary Clinton? Or will he bow out early?Many Democrats blame the uncompromising, self-declared democratic socialist for subjecting Clinton to friendly fire just as she was struggling -- ultimately unsuccessfully -- against the Trump insurgency.Adding to nerves in a country on edge after three tumultuous years under Trump, fears of the coronavirus epidemic prompted both campaigns to cancel election-night rallies.Organizers of a live television debate scheduled Sunday, pitting the fiery Sanders and the moderate Biden, likewise said they would take the extraordinary step of not allowing the usual live audience.For Biden, Tuesday's six-state contest, coming a week after his surprise comeback in voting on Super Tuesday, demonstrated that his once shambolic campaign is in rude health and now ready to face Trump.Michigan in particular -- an industrial giant that Trump won in an upset in 2016 -- was targeted by Biden as a place to put down a marker ahead of the November election.Sanders accused Biden of selling out to corporate interests and ignoring a passionate leftist base.But the former vice president has insisted on steering a centrist line that he says can bring the divided country back together -- and it appears to have paid off.Banking on his credibility as Obama's vice president, he has managed to get out an enthusiastic black vote.But with stories of a hard-knock childhood in Pennsylvania and Delaware frequently featuring in his speeches, Biden also wants to recapture the blue collar white voters that Trump successfully poached from the Democrats in 2016."Biden is putting together the traditional Democratic coalition, and that's still a very powerful one," said Julian Zelizer, a professor of political history at Princeton University and media pundit.Early Tuesday, Biden began his final push by meeting workers at an under-construction automobile plant in Detroit, where he received cheers but also was confronted by one worker.In a startling exchange, the worker, wearing a construction helmet and reflective vest, accused Biden of seeking to take away Americans' firearms."You're full of shit," an angry Biden shot back, insisting that he supports the constitutional right to bear arms."I'm not taking your gun away," he said in the encounter, which Trump supporters quickly pointed to as evidence of Biden's inability to stand pressure -- but supporters saw as a show of mettle."Gimme a break, man," Biden added.Voters came out under the growing shadow of the global coronavirus epidemic, which has infected over 900 people across the United States and killed 28.Sanders and Biden called off customary election-night rallies -- both planned in Cleveland, part of another Rust Belt state, Ohio, which votes next week -- in line with public health warnings from state officials.Their precaution is at odds with Trump, who has vowed to keep holding his campaign's sometimes raucous rallies despite the concerns.Washington state, which has borne the brunt of the crisis and also was going to the polls Tuesday, votes entirely by mail -- an option some experts say should become more widespread as the epidemic grows.Idaho and North Dakota were also voting.Artist and designer Cecilia Covington, 61, was the first person to vote in Precinct 123 in downtown Detroit, braving the drizzle as she arrived at Chrysler Elementary School to vote for Biden."When he wasn't doing well in the polls I was really concerned," she said, adding that his stunning comeback on Super Tuesday "put my confidence back.""We've got to get '45' out of office," she said, referring to the current president.On Super Tuesday, Biden won 10 out of 14 states that voted, giving him a healthy lead even before the latest round of primaries.