The first votes for Ohio's 9th Congressional District are rolling in, and with 13 percent of the expected vote reporting, Merrin is slightly ahead with 46 percent of the vote, while Riedel is second with 39 percent, and Lankeneau is a distant third (14 percent). As Nathaniel wrote earlier, Merrin was a late addition to the contentious race after audio leaked of Riedel calling Trump "arrogant." And as I wrote earlier, Merrin is no stranger to intra-Republican battles.

—Monica Potts, 538

As we wait for the first results to trickle in, let's take a look at the issues voters are thinking about in the state. Among likely primary voters in Ohio, Republicans are much more concerned about immigration than Democrats, according to a poll released last week by Emerson College/The Hill/Nexstar. Specifically, given a list of options, 27 percent of voters who said they were very likely to vote in the Republican primary selected "immigration" as the most important issue facing Ohio, while only 2 percent of very likely Democratic primary voters said the same.

Republican primary voters were also more likely than Democratic primary voters to name "the economy (jobs, inflation, taxes)" as the most important issue facing the state, 39 percent to 27 percent. On the flip side, likely Democratic primary voters were more likely than Republicans to select "abortion access," 15 percent to 3 percent, and "threats to democracy," 18 percent to 7 percent.

—Mary Radcliffe, 538

Polls have now closed across Ohio. The Buckeye State usually counts its early and mail votes first, so expect to see some large vote dumps right off the bat. A word of caution, though: Early and absentee votes are not necessarily representative of the electorate as a whole. We'll want to wait to get more Election Day votes in before drawing any concrete conclusions.

—Cooper Burton, 538

Rounding out our key House races in Ohio as polls close at 7:30, the Republican primary has been pretty uneventful in another Ohio swing seat: the 13th District, which Biden would have carried by 3 percentage points in 2020. Democratic Rep. Emilia Sykes will likely face either former state Sen. Kevin Coughlin or Hudson City Councilor Chris Banweg in November. Not much distinguishes the two, though: They both support Trump and share the same conservative positions on abortion, immigration, guns and more. And they both have raised only modest amounts of money: $332,000 for Coughlin, $280,000 for Banweg. Sykes, by contrast, has pulled in $1.9 million for her reelection bid so far.

—Nathaniel Rakich, 538

California held its statewide primary for president and downballot races on March 5, but it still gets to join in on the March 19 fun. There’s a special election in the 20th Congressional District to fill the vacancy left by former House Speaker Kevin McCarthy, who resigned his seat at the end of 2023. The solidly red seat is all but guaranteed to elect a Republican, but the main question is whether the special will produce a winner today or necessitate a runoff.

That’s because California special elections don’t work exactly like its regular top-two primary elections. Instead, they operate similarly to Louisiana’s jungle primary system. All candidates, regardless of party, run together in a first round — the race happening today — and if one candidate wins a majority, that candidate is elected. But if no candidate wins a majority, a runoff takes place between the top two candidates. Should no one surpass 50 percent today, the two leading contenders will meet on May 21.

In some ways, the March 5 top-two primary served as a dry run for the special because the leading candidates in that race are also on the special election ballot. The favorite is probably Republican state Assemblymember Vince Fong, who led all candidates with 42 percent of the primary vote two weeks ago. Fong is viewed as McCarthy’s hand-picked successor, and he also has Trump’s endorsement. Fellow Republican Tulare County Sheriff Mike Boudreaux narrowly grabbed the second November spot with 24 percent in the primary, so he’s probably the second-most likely candidate to win or advance to a runoff. But in the primary, Boudreaux only ran a little ahead of Democrat Marisa Wood, who won 21 percent, so she could finish ahead of Boudreaux in the special. This is especially true considering that Republican turnout may not be as high today as it was on March 5 because the special won’t coincide with a much-watched GOP presidential primary.

Differences between the set of candidates running in the special and those who ran in the regular primary could also cause consequential shifts in vote share. Four minor Republicans not running in the special won about 5 percent in the primary, while a minor Democrat not running in the special won about 3 percent. Should this support line up more behind the leading contenders in each party, Fong would find himself closer to a majority to win outright, while Wood might overtake Boudreaux for the second spot in a potential runoff. Moreover, voters know how the primary result played out, so that could influence them to consolidate behind the leading candidates. Still, six other lesser candidates are on the special election ballot, so even if they don’t win much of the vote, what share they do take could still help influence the special’s outcome.

—Geoffrey Skelley, 538