Illinois and Ohio primaries 2024: Trump-backed Senate candidate prevails in Ohio primary

538 tracked key House and Senate races, including a California special election.

November’s presidential matchup may be set, but Democrats and Republicans still need to decide who will run in hundreds of downballot races (e.g., for Senate and House) this fall. A batch of these contests were decided on Tuesday, March 19.

Tuesday was primary day in Ohio and Illinois, and in the biggest contest of the day, Republicans chose former President Donald Trump's endorsee Bernie Moreno as their candidate in Ohio’s U.S. Senate race. It was a good night for other Trump endorsees too, as Derek Merrin prevailed in the GOP primary for Ohio's 9th Congressional District, while incumbent Mike Bost is leading his challenger in Illinois's 12th District, as of early Wednesday morning. Plus, a special election in California could have immediate implications for House Republicans’ razor-thin majority.

538 reporters and contributors broke down the election results as they came in with live updates, analysis and commentary. Read our full live blog below.


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Tough night for Chicago progressives

As Cooper mentioned earlier, the Chicago tax reform measure supported by Mayor Johnson is currently behind: With 66 percent of the expected vote in, "no" leads 54 to 46 percent, according to the Associated Press. In another blow to Chicago-area progressives, their preferred candidate is also behind in the Cook County State's Attorney election. According to the Associated Press, progressive Clayton Harris III is losing 52 to 48 percent to moderate retired Judge Eileen O'Neill Burke, with 73 percent of the expected vote counted.

—Mary Radcliffe, 538


Checking in on Democratic women

In Illinois's 6th District, ABC News reports that Manoor Ahmad is projected to lose against incumbent Sean Casten. With a little more than half of the expected vote in, she's gotten about 15 percent of the vote. Ahmad, who was born in Pakistan, had advocated for a permanent cease-fire in the Israel-Hamas War. She'd also endorsed Rep. Ro Khanna's "Poltiical Reform Resolution" and increased federal spending on immigration lawyers and judges as immigration reform. Meanwhile, Casten joined a resolution condeming the Oct. 7 attacks and declaring support for Israel at the beginning of the conflict, but has also called for humanitarian pauses and outlined the accountability he feels is necessary for a cease-fire.

Progressive activist Kina Collins and Chicago City Treasurer Melissa Conyears-Ervin are also projected to lose their bids challenging incumbent Danny Davis in Illinois's 7th District. With over 60 percent of the expected vote reporting, Davis has 52 percent of the vote to Conyears-Ervin's 21 percent and Collins's 19 percent. Davis is almost certain to hold his seat this fall in the safe blue district.

—Monica Potts, 538


Merrin starting to pull away in Ohio's 9th

With 39 percent of the expected vote in, Merrin is slightly ahead in the 9th District with 45 percent of the vote so far, and Riedel is at 42 percent. As my colleagues chatted about earlier, the 9th may be one of the tests of Trump's strength when it comes to swaying voters in the primaries, at least. While his endorsement of Merrin came late in the game, part of the reason Merrin was recruited was because Riedel, the party's previous pick, had been caught being slightly critical of Trump. It's not just a question of whether Trump has remade the party in his image: It's also about whether it tolerates dissent.

—Monica Potts, 538


Safe red seat outside Cincinnati getting close to picking its GOP nominee

With incumbent Rep. Brad Wenstrup retiring from the dark red 2nd District in Ohio, the Republican primary tonight will almost certainly pick the seat's next representative. And with a crowded field of 11 candidates, the winner might even fall short of 30 percent because the vote is so fragmented. With 63 percent of the expected vote reporting, concrete business owner David Taylor leads with 26 percent, while restaurant franchisee Tim O'Hara and hiring agency operator Larry Kidd are running neck-and-neck for second place around 19 percent each. The good news for Taylor is that the places that have reported most of their expected vote are mostly the ones where he's performing worst. Moreover, he holds a big edge in Clermont County, which will probably have around 30 percent of the total primary vote. This race has been a tale of self-funders, as each of the leading three candidates put more than $1 million of their own personal funds into the contest.

—Geoffrey Skelley, 538


How geography has helped make for a close Illinois's 12th District GOP primary

With 68 percent of the expected vote reporting, Bost leads Bailey 53 percent to 47 percent in the Republican primary in Illinois's 12th District. But Bost looks to be on pace for a potentially narrower win — and perhaps could even lose. After the 2020 Census, Illinois Democrats drew a gerrymander that packed more Republican-leaning turf into Bost's 12th District in southern Illinois, which he had represented since 2015. About half of the new-look version of the seat had been in Bost's old district, but much of the eastern part of the seat was new to him. Meanwhile, Bailey's old state Senate seat made up a large chunk of that eastern section, giving him a geographical base of support for this primary despite facing the incumbent Bost.

As things stand, Bost is winning about 70 percent of the vote so far in the area he represented prior to the 2022 election, while Bailey is winning 73 percent in the counties that were in his old state Senate seat. The two are running about even in the remaining turf. The good news for Bost is that more of the primary vote will likely come from his neck of the woods. But the good news for Bailey is that more outstanding votes are likely left to be counted in his area of the district. A back of the envelope calculation based on each candidate's showing so far would put Bost up about 51 percent to 49 percent by the time all is said and done, but that is too close to call.

—Geoffrey Skelley, 538