When can we expect primary election results in Wisconsin and elsewhere?

Most of the attention on Tuesday will be focused on Wisconsin, a battleground state where Republican voters are deciding who will challenge Gov. Tony Evers, a Democrat, in a primary that has become another proxy battle between former President Donald J. Trump and his former vice president, Mike Pence.

Polls close in Wisconsin at 9 p.m. Eastern time. While it is hard to predict when we might get returns on election night, there are factors that can give us clues: How much of the vote is expected by mail, what rules the state has about when ballots can be counted and, of course, how close a race is.

The Republican primary for governor has been a close one, with Tim Michels and Rebecca Kleefisch leading in a race where a central campaign issue has been the false notion that Mr. Trump’s 2020 defeat can be decertified.

Mr. Trump endorsed Mr. Michels, a construction magnate who has said he would consider decertifying the 2020 results — something that cannot legally be done. Ms. Kleefisch, who is endorsed by Mr. Pence, has often found herself explaining this to voters. Trailing them both is Tim Ramthun, the state’s leading proponent of decertification.

Milwaukee, Ozaukee, Washington and Waukesha counties are home to the state’s largest concentration of Republican voters, so a race call in the governor’s primary may hinge on how voting goes in those areas: High turnout or unforeseen issues could make it hard to get a clear picture of the race’s outcome early in the evening.

With Republicans largely rejecting mail voting since Mr. Trump sowed doubts about the method in 2020, the delays associated with counting absentee ballots are unlikely to be a factor. But that is not a guarantee.

Election officials in Wisconsin could not start processing absentee ballots until polls opened on Tuesday morning. And many of the state’s major cities, including Milwaukee and Green Bay, do not publish any results from ballots cast during early, in-person voting and absentee ballots until all are counted, according to Riley Vetterkind, the Wisconsin Elections Commission’s public information officer. That can go late.

Ms. Kleefisch is expected to perform strongly in Milwaukee and its suburbs, so depending on how close the race is, those late batches of absentee and early ballots could come into play.

As of Monday, almost 278,000 mail ballots had been received by officials in Wisconsin — about a third as many as were returned in the April 2020 primary, early in the pandemic.

Vermont’s polls will be the first of the night to close at 7 p.m. Eastern time and officials can’t start tabulating mail ballots until then. Mail voting is up over previous midterm elections, according to Eric Covey, the chief of staff for Vermont’s secretary of state. Mail ballots could have a significant impact in tight races, like the Democratic primary for the state’s only House seat, and it could be late into Tuesday night before preliminary results are available in that race.

But Vermont officials expect that most ballots will be counted before midnight, helped by a rule that mail ballots must be received by the end of Election Day. All towns and municipalities with more than 1,000 residents are required to use electronic vote tabulators to count ballots, which will also speed up the process.

In both Vermont and Connecticut, ballot counting is handled by towns, rather than counties. Many town officials in both states wait until all mail and in-person votes have been counted to release results, according to Stephen Ohlemacher, the election decision editor for The Associated Press. That could delay the release of any results in places with a lot of mail voting.

Polls close in Connecticut at 8 p.m. Eastern time. It is up to local officials to decide whether to start counting mail ballots before or after in-person voting ends. No mail ballots received after polls close will be counted.

Mr. Ohlemacher noted that Connecticut has struggled to count mail votes in past elections. In 2018, it took officials until 4 a.m. the morning after Election Day to count 89 percent of votes. In November 2020, more than 45 percent of the vote was uncounted by midnight on election night.

Election officials everywhere would like to remind us that all the results we get Tuesday night are unofficial. That is unlikely to change any race calls that are made, but it typically takes states weeks to certify official results.

Reid J. Epstein contributed reporting.