This has been updated with the latest news.

Amid the expanding novel coronavirus crisis, some states are going full-steam ahead with primaries (including three of the four holding presidential contests Tuesday). Others are delaying theirs for months, like Ohio did the day before it was set to hold its primary.

President Trump thinks they should go on: “I think postponing is unnecessary,” he said Monday.

What’s the impact of this in a still-not-settled Democratic presidential primary? Former vice president Joe Biden is trying get an insurmountable delegate lead over Sen. Bernie Sanders (I-Vt.). To do that, Biden needs primaries held sooner rather than later, and he needs his supporters to feel comfortable voting.

Is that going to happen? Let’s look at what we know.

Biden gets his support from older voters

That would be good news for Biden if there wasn’t a pandemic primarily affecting older people. A Monmouth University poll in Arizona, one of the states voting Tuesday, finds Sanders leads Biden by nearly 30 percentage points over Democratic voters under 50 likely to vote. He also leads Biden by seven percentage points among Latino voters. Yet Biden is leading Sanders among all Arizona Democrats likely to vote by nearly 20 percentage points. That’s because white voters and voters over 50 favor Biden, and they’re more likely to vote in primaries than young or Latino voters.

Does the coronavirus upend that long-held political calculation? The virus has more serious complications for older people, and on Monday the Trump administration issued recommendations of avoiding gatherings of more than 10 people. There easily could be that many people in a single polling location, especially if there are lines to vote.

Of the states voting Tuesday, Kaiser Family Foundation estimates around 40 percent (Illinois) to 46.5 percent (Florida) of the population are at risk.

Most states have moved polling locations away from their traditional locations, such as senior centers. Why would seniors leave their homes to venture out to a place the CDC deems potentially unsafe?

Sanders has used his support from younger Democrats as a primary reason for staying in the race. “We are winning the generational struggle,” he said in Sunday’s presidential debate. To Biden, he said: “I have my doubts about how you win a general election against Trump — who will be a very, very tough opponent — unless you have energy, excitement, the largest voter turnout in history.”

Could coronavirus affect Sanders’s trend of doing well among young voters and Biden doing well among older voters — but not enough to run away with the nomination and settle Sanders’s doubts he can defeat Trump?

There are potential political downsides for Sanders, too. Wyoming holds its Democratic nomination April 4. It’s a caucus, which has benefited Sanders because caucuses favor passionate voters willing to spend hours to cast their vote. But Wyoming canceled the in-person portion of the caucus, asking people instead to mail in ballots and rank their choices. (Before the coronavirus, Nevada had a mixture of early voting, mail-in voting and in-person caucus. Sanders handily won that state.)

Some Sanders supporters are pushing to postpone all primaries until it’s safer to vote. At almost the last minute, Ohio officials did do just that, postponing all in-person voting from Tuesday to June. (Election officials of the three states holding primaries have said voting doesn’t mean people stay in one space, like a concert, but rather come and go quickly.)

Early voting has been going strong in many states

Early voting already is happening in the four states voting Tuesday — Arizona, Florida, Illinois and Ohio. It looks like more voters are taking advantage of that this year, which could be good news for Biden.

In Arizona, Monmouth University found half of likely Arizona primary voters already cast their ballots. A large chunk of them prefer Biden, by 50 percent to Sanders’s 27 percent.

In Ohio, the secretary of state calculates early and mail-in voting is up significantly. A week before Tuesday, 44,000 more people requested absentee ballots than at the same time in 2016. In-person early voting has doubled from 2016 to 2020.

In Chicago, early voting set a post-World War II record, reports the Chicago Tribune.

Could that mean Biden banks up enough support to win these primaries even if turnout among his base goes way down on the actual Election Day?

Maybe. Florida seems to favor Biden with older voters and moderate Latino voters. Reports there say early voting has been slow, especially in the Democratic stronghold of South Florida.

Florida’s top election officials, who are Republicans, did not heed calls from voting advocates to extend early voting beyond the weekend. It’s too late to mail in a ballot, reports the Miami Herald. That adds to the complications for actual Election Day in Florida: Some counties say so many poll workers have quit they’ve had to consolidate polling locations, potentially crowding even more people together. Florida’s secretary of state said the election will go on given almost 2 million people have already voted early.

Biden surrogates have been out in Florida encouraging people to vote. “I’m comfortable being out here, casting my vote early,” said Rep. Debbie Wasserman Schultz (D-Fla.), as she voted “and really want to encourage folks that if they’re comfortable, that they can have that confidence, too.”

There are pushes for states to make mail-in ballots an option

Well before coronavirus, there has been a trend in states to allow at least some voting by mail. At least 21 states have provisions to conduct smaller elections entirely by mail if needed, according to the National Conference of State Legislatures.

Five states automatically mail ballots to registered voters. One of those is Washington state, which conducted its primary last week by mail even though it was the epicenter of the coronavirus outbreak.

It’s not clear which candidate a mail-in would boost in the Democratic primary. We do know vote-by-mail states take much longer to count. Results are still pending in Washington, with a close race between Biden and Sanders. That could draw out a primary Biden and Democratic Party leaders are eager to end.

Voting by mail is not as easy as simply mailing ballots. Arizona allows voting by mail in certain circumstances. But in Maricopa County, which has a large percentage of Latino voters, a judge blocked election officials from mailing ballots after the Republican attorney general said they didn’t have the authority to mail ballots to people who didn’t request them.

Correction: An earlier version of this post misstated how many states have provisions to conduct some elections entirely by mail if needed. Twenty-one states do indeed have some provisions, but the NCSL says those are for smaller elections. Only five states are fully capable of running a statewide primary by mail.