Former Vice President Joe Biden scored decisive wins over U.S. Sen. Bernie Sanders in the Florida, Illinois and Arizona primaries on Super Tuesday III, increasing the pressure on the independent Vermont senator to concede the race.

Biden won all of the delegates available on March 17: Florida’s 219, 155 in Illinois, and Arizona’s 155.

It marked the third week in a row Biden began piling up wins after his victory in South Carolina last month revived his once-flagging campaign. Since then, most of his party’s establishment lined up behind him as the best option to unseat President Donald Trump in November.

The coronavirus forced officials to scrap Democratic presidential primary voting altogether in Ohio and hampered some balloting in Super Tuesday III’s states. The global pandemic has shut down large swaths of American life threatened to disrupt elections around the country for months to come.

Ohio called off its state's primary just hours before polls were set to open as the federal government urged Americans not to gather in groups of 10 or more and asked older people to stay home entirely.

»Live results from March 17, 2020 presidential primaries

Democratic National Committee Chairman Tom Perez blasted Ohio's unprecedented move for breeding “more chaos and confusion." He sought to head off more states from taking similar actions, urging those with upcoming primaries to expand vote-by-mail and absentee balloting, as well as polling station hours, so that efforts to stop the spread of the coronavirus don't further derail his party's contest for the right to face President Donald Trump in November.

“The right to vote is the foundation of our democracy, and we must do everything we can to protect and expand that right instead of bringing our democratic process to a halt,” Perez said in a statement. Four other states — Louisiana, Georgia, Kentucky and Maryland — have already moved to push back their primaries, and others could follow suit.

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In Illinois, an elections official and the governor traded blame over who was responsible for chaos at the polls. In Okaloosa County in Florida's Panhandle, two dozen poll workers dropped out, leaving Elections Supervisor Paul Lux's staff scrambling to train replacements.

The coronavirus has cast a shadow over the Democratic primary race as debates over policy minutiae have taken a back seat to issues of life and death.

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Still unclear Tuesday was the extent to which the coronavirus would affect turnout.

Millions of voters have already participated in some form of early voting. But there were signs on Tuesday that voters — and poll workers — were staying home. In Burbank, a small community southwest of Chicago, most of the voting stations stood empty at 8 a.m. Only 17 people had voted, a pace that officials said was unusually slow.

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In Florida, Palm Beach County Elections Supervisor Wendy Sartori Link said three polling sites had to be moved and four opened significantly late because workers didn't show up and hadn't given notice.

In Illinois, there was a push to relocate about 50 Chicago-area polling places after locations canceled at the last minute. The chaos at the city's polls led to fingerpointing between a city elections officials and Illinois' Democratic governor after days of public debate over whether the state's primary should be postponed because of the coronavirus threat.

Biden senior adviser Anita Dunn said the former vice president's campaign watched early reports of low Chicago turnout with some concern, but those worries abated as voters cast ballots throughout the day.

"You hear there's no rush hour" at the polls, "and then you realize, well, there's no rush hour at all," because so many voters are working at home, Dunn said.

Kate Bedingfield, Biden's deputy campaign manager, released a memo Tuesday afternoon predicting that "overall turnout will be roughly on pace for 2016 in Arizona and Florida and roughly on pace for 2018 in Illinois, and that voter turnout in all three states will reflect the population at large." Bedingfield cited strong early voting numbers in all three states.

Sanders, the last Democrat standing between Biden and the nomination, isn't planning to drop out, with his team seeing no downside to staying in the race as they assess how the coming days and weeks unfold.

He faces, however, an increasingly tough path to the nomination. About half of the delegates in the Democratic primary have already been awarded and, if Biden has another big night Tuesday, he will pad an already large and perhaps insurmountable lead. Sanders trails Biden by more than 150 delegates nationally, meaning he'd need to win more than 57% of those yet to be allocated to clinch the Democratic nomination.

The coronavirus also could amplify calls for Sanders to drop out of the race, especially if Biden comes out of Tuesday night's primaries in an even stronger position, Lehrich noted.

“It all feels like a bizarre formality given the moment — a pointless subplot with a foregone conclusion, in the midst of an existential threat,” he said.

The Associated Press contributed to this report.