Want to know who won the presidential race on election night? Get ready to wait.

It’s a familiar election night routine: Polls close, and everyone wants to know who won — immediately. Every minute matters for Americans anxiously awaiting the results. News organizations race to meet the demand by using complex statistical models to “call” the winner long before all the votes are counted.

But get comfortable waiting: Instant electoral gratification is about to become a thing of the past.

A new Pennsylvania law that allows any voter to cast a ballot by mail, along with a surge in requests for mail-in ballots driven by fears of voting in person during the coronavirus pandemic, has set up a 2020 election in which everyone could be left waiting for days before results are known.

That might not bother the public much when it comes to the June 2 primary, with a Democratic presidential contest that has already been effectively decided. But when President Donald Trump and former Vice President Joe Biden face off in the fall, and all eyes turn to the critical swing state of Pennsylvania, delays could effectively leave the race for the White House in limbo for days.

“If nothing changes before November, I would bet my house there would be no way anybody could responsibly call the presidential race [on election night],” said Forrest Lehman, elections director for Lycoming County, in central Pennsylvania.

The new law, which also changes how and when mail-in votes are counted, already stood to wreak havoc on the public’s expectation for quick results.

“No county wants to be the reason we don’t know the leader of the free world on election night,” Lee Soltysiak, Montgomery County’s chief operating officer and clerk of its election board, said in January. “And that’s the position, depending on the margin, we’re all likely to be in.”

» READ MORE: From January — Pennsylvania’s presidential election could be too close to call for days because of a new law

Then the coronavirus hit. The number of polling places are being cut. Requests for mail ballots have gone through the roof.

Soltysiak laughed when reminded of what he said in January.

“We’re not in a better place,” he said this week. “All of the challenges that we’re preparing to face still exist — and we have layered on top of them those that go along with volume and the pandemic.”

Every election night, news outlets try to project winners using unofficial results from precincts, surveys of voters leaving polling places, turnout data, and more. (Official results aren’t certified until weeks later.)

But some of that modeling depends on people voting in person, and data from past elections will be less useful this year now that Pennsylvania has changed how they are run. Not to mention that voter behavior is harder to predict during a pandemic. The crisis also means it will take even longer than expected to count mail ballots, county elections officials said.

Philadelphia elections officials, for example, expect mail ballots to make up a majority of the vote, and they won’t even start counting them until the day after the election. Several large counties, including Bucks, Chester, and Montgomery, plan to start counting absentee ballots on election day, but expect to take at least another day or two before finishing.

» READ MORE: Philly voters have requested more mail ballots than all of Pennsylvania did in 2016

Christine Reuther, a Delaware County councilwoman, said “it would be unreasonable for people to expect results” from her county before Saturday.

Four days after the election.

The only silver lining for the primary, officials said, is that Biden and Trump are all but assured to win their party nominations, which could lower turnout and the number of mail ballots to count.

But that might also obscure the magnitude of the problem looming in November, when millions will anxiously await the results from Pennsylvania.

“We don’t have any choice at this point but to take our lumps on June 2 and then learn lessons from it and apply them forward,” Lehman said.

“That’s the only hope I have,” he added. “But I don’t have a whole lot of it.”

The time it takes to count ballots isn’t a sign of fraud, corruption, or any other failure of the electoral system. Rather, it’s a direct result of reforms to help expand access to voting.

In the past, the vast majority of votes were cast in person. Pennsylvania had one of the most restrictive absentee voting systems in the country, and only about 5% of votes in any election were cast by mail. So when polling places sent results back to county elections offices, they accounted for almost all the votes.

The new law enacted last year changes that.

It was a bipartisan move to make voting more flexible and convenient. It will also dramatically increase the number of mail ballots. (Due to a quirk in the law, Pennsylvania technically has two kinds of mail ballots, “absentee” and “mail-in,” that are functionally the same for voters.)

Mail ballots also take much longer to count than in-person votes. Physical voting machines keep track of votes as they are cast and spit out a summary at the end of the night. But mail ballots require opening two different envelopes and then scanning the paper ballots. And some ballots need to be counted by hand, either due to voter error or problems with scanners.

“It will definitely not be same-night election results that people are used to. We will certainly be well into the next day," said Gail Humphrey, the chief clerk for Bucks County. “Those scanners can jam.”

“If there’s absolutely nothing that happens by technology that we didn’t foresee,” she said, “we’ll still be at least, bare minimum, into the next day still counting.”

The pandemic led to a volume of mail ballot requests that is far exceeding officials’ expectations. As of Wednesday, Pennsylvania voters had sent in almost 1.6 million applications for mail ballots, far exceeding the total of 107,000 in the 2016 primary.

That means a significant strain on counties to actually tally them, just as social distancing guidelines make gathering workers to do so that much harder.

“The number of people you’re going to have being able to canvass, or to open up envelopes even, at an eight-foot table is pretty much one. And one at the next table,” said Randall O. Wenger, chief clerk of the Lancaster County Board of Elections. “It’s going to impact and slow down that process as well.”

“I don’t have any delusion that we’re going to have [all the ballots] opened and scanned and adjudicated that same day," Wenger said. "Not going to happen.”

Counties also have to figure out how many people they can even dedicate to counting ballots, given how messy in-person voting at polling places is likely to be. In Philadelphia, which will have 77% fewer polling places this year, elections staff will be too busy to count mail ballots, said Lisa Deeley, chair of the City Commissioners, who run elections.

» READ MORE: Philly will have way fewer polling places for next month’s primary because of coronavirus. Find yours here.

“It’s unrealistic to think I’m going to have people to go sit and count ballots,” she said. “Election day is going to be quite the challenge, and it’s going to pretty much take up all our bandwidth on election day.”

Things could be even worse in November, officials said. It remains to be seen if the outbreak will have eased by then, or if it will be spiking anew. What is certain, though, is that the volume of mail ballots will be much higher because of higher turnout for the general election. And the presidential election in Pennsylvania will likely be decided by razor-thin margins, after Trump won by less than 1% of the votes cast in 2016.

There are two ways to lessen the waiting time, elections officials said: Start counting earlier and reduce the time it takes.

Reducing the processing time requires money to buy more machines and hire more staff to operate them. So starting earlier is the simpler fix.

But when the election law was changed last year, it required counties to wait until 8 p.m. before starting to count mail ballots.

Pennsylvania Secretary of State Kathy Boockvar, who oversees elections, said at the time that she believed counties could manage the task. But pressure from the counties led state lawmakers to make a change in March: Counties can now begin counting mail ballots at 7 a.m. on election day, when polls open.

“I’ve only got 29 precincts, it’s not going to take me days and days,” said Florence Kellett, director of elections in Wyoming County.

Kellett and officials in several other counties said they would begin counting during election day. Still, they said lawmakers should update the law again, to allow them to start counting ballots days or even weeks earlier.

In recent weeks, Boockvar has taken up that call.

The 7 a.m. change helps, “but I don’t think it’s going to be sufficient for many counties,” she told reporters Wednesday during a conference call. “I think some of the races that are close, we will get results quickly. But if there are close races, it may take a couple of days.”

Staff writer Jonathan Tamari contributed to this article.