Polls have closed in Brazil. Here’s what happens next.

The polls have closed in Brazil’s high-stakes presidential election. Now here is what to expect next.

Because Brazil is the only country in the world that uses a fully electronic voting system, the counting of ballots has historically happened relatively quickly, particularly for a country so vast. Election officials said on Sunday that they hoped to be able to call the contest by 7 p.m. Eastern time.

At hundreds of thousands of polling stations across the country, officials aggregate the vote results from each voting machine and transmit those tallies to the federal election agency in Brasília, the nation’s capital.

On Sunday, all polling stations will close at the same time, though the country is spread across three time zones. Yet the results will trickle in over several hours and, significantly, the early returns are expected to skew toward President Jair Bolsonaro, the far-right incumbent.

Why? The answer, in large part, has to do with Brazil’s internet infrastructure.

Support for Mr. Bolsonaro and other right-wing candidates has historically been stronger in the more developed, wealthier regions in Brazil, where there are more robust internet connections than in the poorer regions that tend to favor leftists candidates like Luiz Inácio Lula da Silva, Mr. Bolsonaro’s challenger on Sunday.

That is particularly true in Brazil’s vast, poor, rural northeast, which accounts for about 27 percent of voters and has long been Mr. da Silva’s stronghold.

As a result, Brazilians have become accustomed to watching conservative candidates get out to early leads after the polls close and then see leftist candidates close the gap — or sometimes overtake their opponents — toward the end of the vote counts.

But Mr. Bolsonaro has repeatedly pointed to that trend — without any credible evidence — as an indication of fraud, part of a broader, yearslong effort to attack Brazil’s electronic voting system.

In the 2014 presidential election, a center-right candidate led for hours in the vote returns until the leftist candidate from Mr. da Silva’s party eventually overtook him and won the presidency. The losing candidate claimed something was amiss and demanded an audit, and Mr. Bolsonaro, a congressman at the time, championed the cause.

The trend happened again in the first round of voting earlier this month. Mr. Bolsonaro led at the start of counting until Mr. da Silva overtook him.

Days later, Mr. Bolsonaro held up a graph of the vote returns and suggested he had been the victim of fraud. The pattern in the vote returns, he said, looked “quite like an algorithm.”

There is no evidence of fraud in Brazil’s electronic voting machines since they were introduced in 1996.