Several key congressional races have dragged on long past the end of the presidential contest. The House remains contested, though Republicans have claimed more seats so far, and vote counting continues in three Senate races in swing states.

Here are updates on some of the races that were still not called by Friday afternoon:

Pennsylvania’s Senate race

Dave McCormick, the Republican candidate, has a slim advantage in the tally so far and has claimed victory, but the Democratic incumbent, Senator Bob Casey, has not conceded. The New York Times has not called the race.

The candidates remain about 39,000 votes apart, a difference of just more than half a percentage point. On Thursday, the state reported that some 100,000 provisional, military, overseas and Election Day ballots were still uncounted. That included around 33,000 provisional ballots in the state’s largest counties, Philadelphia and Allegheny, which includes Pittsburgh.

Counting the remaining ballots could stretch into next week, local officials said. If the margin winds up within half a percentage point, the race could go to a recount.

Arizona’s Senate race

Most voters cast ballots by mail in Arizona, and by Friday there were still more than 700,000 ballots remaining to be counted, according to the secretary of state’s office. In the Senate race, the Democrat, Ruben Gallego, was ahead of the Republican, Kari Lake, by nearly 41,000 votes in the tally so far.

The bulk of the votes remaining to be counted are in Maricopa and Pima Counties, which contain Phoenix and Tucson and tend to lean more Democratic. The later-arriving mail ballots in Maricopa, however, have been leaning more Republican.

Nevada’s Senate race

Tens of thousands of mail-in ballots remain to be tallied, mostly in Clark County, which includes Las Vegas, and Washoe County, which includes Reno.

Those votes will most likely lean Democratic, suggesting that the one-point advantage that Jacky Rosen, the incumbent Democrat, currently holds over Sam Brown, her Republican challenger, is likely to grow.

At this point, most rural counties have finished counting the mail-in ballots they have received. Postmarked ballots are allowed to arrive until Saturday, though the remaining numbers are expected to be small, and voters have until Tuesday to fix any identification issues with their ballots.

House races

The House remains up for grabs, though Republicans need only seven more seats for a majority. Twenty-five seats have not been decided for either party. Of those, 10 are in California and four are in Arizona, where counting will continue into next week.

• Nick Begich, a Republican, is ahead in the vote tally in the Alaska at-large race, which was flipped by Representative Mary Peltola two years ago. But the state is still accepting absentee ballots that were mailed by Election Day. Carol Beecher, a state elections official, said Alaska would post results from the bulk of uncounted votes in this race on Tuesday.

• In Maine’s Second Congressional District, Representative Jared Golden, a Democrat, is leading Austin Theriault, his Republican challenger, by fewer than 2,000 votes. But because the race is so close, the state’s ranked-choice voting — which allows voters to select multiple candidates in order of preference — comes into play. If a voter’s first choice was a write-in candidate or was left blank, that vote will now be reallocated to Mr. Golden or Mr. Theriault if either was the voter’s second choice. The process will take some time.

• Marcy Kaptur, the Democratic incumbent in Ohio’s Ninth Congressional District, holds a small lead over the Republican, Derek Merrin — around 1,000 votes, as of results from Wednesday — but there are still thousands of provisional ballots that must be reviewed and counted.

• Representative Marie Gluesenkamp Perez is ahead in the vote count in Washington’s Third Congressional District, a seat she flipped for Democrats in 2022. But while her advantage stood at 11,000 votes, there were a significant number of votes remaining to be counted — an estimated 40,000 to 50,000 ballots, as of late Thursday, not counting ballots postmarked before the election that have yet to arrive. The vast majority of the uncounted votes are in Clark County, where Ms. Gluesenkamp Perez leads.

• California, where 10 races remain uncalled, will count all ballots postmarked by Election Day as long as they arrive by Tuesday, so the count won’t be complete until then at the earliest. And some counties won’t post updated results at all until Tuesday, because of the Veterans Day holiday.

• Election officials in Maricopa County, Arizona’s largest county, said before the election that they expected counting to take at least a week. And Pima County officials said this year’s two-page ballot has slowed down tabulation and made it harder to estimate when they might finish. That leaves several competitive congressional races hanging in the balance, as well as the state’s Senate race and presidential contest.

Jacob Meschke contributed reporting.