Polls have now closed across Illinois, where we'll be monitoring several U.S. House primaries, as well as a closely-watched referendum in Chicago. Rep. Mike Bost is facing a challenge from his right, while Rep. Danny Davis is facing one from his left.

—Cooper Burton, 538

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

Democrats (and allied independents) currently hold a bare majority in the U.S. Senate, with 51 seats to Republicans’ 49. But control of the chamber is at stake in November, and the Senate race in Ohio is one of a few competitive contests that could decide control of the chamber.

Three Republican contenders are facing off today for a chance to challenge incumbent Democrat Sherrod Brown in that contest: Matt Dolan, a state legislator running with the endorsement of former Ohio Sen. Rob Portman; Frank LaRose, the current Ohio Secretary of State running on a campaign of conservatism and electability; and Bernie Moreno, a businessman with endorsements from Trump, a dozen members of Congress including Ohio Sen. J.D. Vance and the Club for Growth PAC, one of the oldest conservative PACs in the country.

Moreno, who appeared alongside Trump in several campaign events this past weekend, has gained significant ground in the polls since the former president endorsed him in mid-December. Then, he was polling at 16 percent in 538’s polling average — and now he’s hovering in the mid- to-high-20s. Democrats view Moreno as the weakest candidate for the general election and last week began airing a television ad intended to boost his standing by “attacking” his conservative record and support for Trump ahead of Tuesday's primary.

But the polls show a tied race between Dolan and Moreno, who each lead LaRose by 10 percentage points. That’s too close for polls to provide a reliable signal of who is decisively leading: Per our database of historical polls, surveys of Senate primaries miss the margin between the winner and runner-up by 6.5 points on average.

Looking ahead to the general election, the winner of today’s Republican primary matters not just in deciding who might be Ohio’s next senator, but in deciding control of the Senate come 2025. Since West Virginia Democratic Sen. Joe Manchin decided to retire, prognosticators largely expect the Republicans to pick up at least one seat this November. That means Democrats and Republicans start their fight for the majority from a 50-50 tie, and Democrats need to at least hold on to the rest of their endangered seats — and for Biden to win — to maintain control.

Ohio is a red state, but Brown has managed to run ahead of expectations in previous cycles. So has fellow endangered Democrat, Montana Sen. Jon Tester. But neither of them have run in a presidential cycle since 2012, when President Barack Obama pulled off a surprising reelection and Democrats gained two seats in the Senate. Brown will face not just the strength of his opponent in November, but the partisanship of his constituents. The Cook Political Report rates the Ohio Senate race a toss-up.

—G. Elliott Morris, 538