Joe Biden has a chance to further hinder Bernie Sanders’ presidential hopes Tuesday as national health concerns cast a gloomy backdrop on a crucial day in the 2020 Democratic primary.

Tuesday’s voting has created a tension between public health concerns and voting access in a way that was unthinkable just months ago.

At the same time, poll worker issues and shifting polling sites troubled experts in what has been described as an unprecedented situation. Despite continuing novel coronavirus fears, three states—Arizona, Illinois, and Florida—are set to vote Tuesday, while Ohio officials tried Monday to postpone their election day deadline to June 2.

“In the ideal world, people would absolutely not be going to election stations right now,” said Adam Green, co-founder of the Progressive Change Campaign Committee, which supported Sen. Elizabeth Warren (D-MA) and has encouraged Sanders (I-VT) to stay in the race. “But in a good democratic world, people should be voting, right? I think it’s just a genuine tension right now.”

On Sunday, the Centers for Disease Control and Prevention released updated guidance urging “for the next 8 weeks, organizers (whether groups or individuals) cancel or postpone in-person events that consist of 50 people or more.” On Monday, President Donald Trump said people should avoid “gathering in groups of more than 10 people.”

Leading election officials in the Tuesday states, including Ohio, had pledged in a statement on the Friday before the primary that they were “confident that voters in our states can safely and securely cast their ballots in this election,” and had been encouraging early voting options.

But the CDC guidelines, Ohio Gov. Mike DeWine said on Monday, made it clear the state could not follow them and also hold in person voting on Tuesday. Between now and June 2, absentee ballot voting would be permitted DeWine said.

“This should extend the period of time so that people will not have to choose between their constitutional rights and their health,” DeWine said.

But confusion about the Ohio election’s fate continued into Monday night. Despite Gov. DeWine’s earlier urging, The Columbus Dispatch reported after 7 p.m. that a Franklin County judge sided against the governor’s hopes and the election was still on.

DeWine refused to give up, however. Just after 10 p.m. he said on Twitter an Ohio official “will order the polls closed as a health emergency.”

“During this time when we face an unprecedented public health crisis, to conduct an election tomorrow would force poll workers and voters to place themselves at an unacceptable health risk of contracting coronavirus,” DeWine tweeted.

Health concerns had already troubled the primary process with two states set to vote in the coming weeks in Louisiana and Georgia deciding to postpone their primaries to June 20 and May 19, respectively. Kentucky officials also announced Monday they would delay their primary from May 19 to June 23.

Heading into this week, Biden has already seen a substantial lead in delegates over Sanders. According to the Associated Press, the former vice president has won 894 delegates to Sanders’ 743.

That nomination battle is continuing to play out against an uncertain future for many Americans as states work to assuage fears relating to the virus.

“All of our social and civil life is going to be entirely disrupted,” said Lawrence Gostin, director of the O’Neill Institute for National and Global Health Law at Georgetown University. “Voting is extraordinarily important, but it could pose a health risk.”

Despite Biden’s delegate total still being far from the number he needs to clinch the nomination, even a modest lead can be incredibly difficult for a challenger to overcome because of how Democrats allocate their delegates.

The coronavirus is a looming concern as voters head to the polls, and the Sanders campaign hasn’t been shy in recent days about how it could impact voting.

On Saturday night during a virtual fireside chat, campaign manager Faiz Shakir said: “We are told that the other four states on March 17 will go forward as of now. Who knows, we’ll see what happens in a few days. But if they do go forward, and if you are healthy, we’d ask you to go to the polls and please vote and then wash your hands.”

Tensions returned on Sunday when Biden senior adviser Symone Sanders said in a clip of a CNN interview tweeted out by Sanders national press secretary Briahna Joy Gray that “the CDC and folks have said it’s safe out there for Tuesday.”

That sentiment had been expressed in a joint statement Friday by the leading election officials in the Tuesday voting states, but Joy Gray pushed back on the CDC portion of Sanders’ comment.

“That’s wrong,” Joy Gray tweeted Sunday. “The only guidance we have so far is that we should not gather in groups of 50 people or more. I’m sure it’s an honest mistake, but this is a public health crisis.”

Those thoughts, and the platform they were made on, caused unease Monday morning from Kristen Clarke, the president and executive director of the Lawyers’ Committee for Civil Rights Under Law.

“In a moment where you have four states in the midst of conducting primary elections tomorrow, statements like this are deeply concerning,” Clarke said before Ohio moved to push off its primary until June. “I think that social media plays a role here in ensuring that people are not manipulating the platform to discourage voting, discourage voters from participating.”

The debate night remark also drew quick concern from some including Neera Tanden, president of the Center for American Progress, who tweeted just after midnight “Is the Sanders campaign telling people not to vote on Tuesday?”

“This is a low point. Even for you,” Joy Gray responded. “I don’t know if you love or care about any immune compromised people, but I do. Please try not to make this a craven political issue for once.”

But by the end of the day Monday, Ohio was backtracking on its earlier safety claim as it worked to move back in person voting to June 2.

In recent days, Sanders has been willing to admit that the primary hasn’t gone the way he had once hoped. But he and his larger campaign orbit have continued to be defiant about Biden and the challenges they fear he can have in the general election.

Tuesday’s contests may also prove to be a difficult test for Sanders. During his 2016 primary run against former Secretary of State Hillary Clinton, the Vermont Independent carried none of them as his chances at winning the Democratic nomination dwindled.

A strong showing from Biden Tuesday would become the latest surge of support over a month-long span that completely reshaped the Democratic race. Starting in South Carolina and winding through decisive wins on Super Tuesday and wins that wounded Sanders in Michigan and Missouri, Biden has gone from risking becoming an afterthought to the likely Democratic nominee.

Both Biden and Sanders held virtual campaign events Monday as they tried to make their final pitch to voters in a way neither would have preferred under normal circumstances.

The Sanders event was a musical affair with Jim James of My Morning Jacket playing on a large stage with a rotating set of Sanders pictures behind him before Neil Young made his own remote appearance after surrogates championed the senator’s cause. James played on a large stage with a rotating set of Sanders pictures behind him.

During Sanders’ personal segment, he took time to once again disagree with Biden’s electability argument.

“We are reaching out to people who are non-traditional type voters,” Sanders said. “Now to be honest with you, we’ve had problems getting some of those non-traditional voters to vote in the primaries, but I think they’ll be there on election day.”

On Monday night, Biden and his wife, Dr. Jill Biden, held a tele-town hall with community members from Arizona, Florida, Illinois, and Ohio, part of an ongoing series of remote events his campaign is test-running in the wake of the coronavirus outbreak. Former Surgeon General Vivek Murthy also joined the call.

“We’re going to follow the guidelines offered by state public health officials,” Biden said, acknowledging voters may feel worried about standing in line to cast their ballots during the pandemic. “Three of the states believe that can be done by separation in lines and washing down machines, etc.”

As another day passes and fears about the virus continue, concerns about how it could impact voting well into the year are becoming apparent.

The virus is “absolutely going to impede the vote,” said Gostin, the Georgetown professor, and it may haunt more than just the immediate future of the 2020 Democratic contests.

“It’s not just the primaries,” he said. “There’s every possibility that COVID-19 will come raging back seasonally and reach another zenith in November during the presidential election.”

—With additional reporting by Hanna Trudo