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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Checking in on the Ohio state House races

I mentioned earlier that Merrin had been involved in a speaker fight in Ohio that he lost when another candidate, Stephens, won the backing of Democrats to hold a more moderate speakership. Twenty-two Republicans in the state House joined in voting for Stephens, including Stephens himself, and were dubbed the Blue 22. They were censured by the state party. Of those running again, 12 face primary challengers. By our count, 8 of the Blue 22 running for reelection are currently ahead and 4 are running behind their challengers, according to the Ohio Secretary of State. Stephens is running unopposed, but that could spell doom for his speakership.

—Monica Potts, 538


I regret to inform you that the Amish did not overwhelmingly choose Haley

The earlier result I mentioned that appeared to show Nikki Haley had won heavily Amish Holmes County, Ohio, looks to have been a reporting error. The error has been corrected, and updated results from the Associated Press show Trump leading the county 82-11 percent with over 95 percent of the vote reporting.

—Mary Radcliffe, 538


Merrin projected to win in Ohio's 9th

Merrin, the last-minute addition to the race, is projected to win the primary in Ohio's 9th District, according to ABC News. He will face incumbent Kaptor. Despite her incumbency, the seat could be tough for the long-serving Democrat to hold onto. As Nathaniel wrote earlier, Republicans in the state redrew the district to make it more Republican. But finding the right candidate has been tough for them: They'll be holding out hope that Merrin, who's been involved in his own intraparty battles in the state, will win this November.

—Monica Potts, 538


Former deputy Democratic leader ousted in the Illinois state House

In Illinois’s 31st state House District, a battle has been brewing between longtime state representative Mary Flowers and state House Speaker Chris Welch. Flowers was the deputy Democratic leader of the chamber from 2020-2023, but was stripped of her leadership position in May 2023 after allegations of abusive conduct toward other members and staff. This year, Speaker Welch led an effort to oust her from the chamber, directing hundreds of thousands of dollars toward her challenger, Michael Crawford, and encouraging outside groups, particularly unions, to support Crawford.

The effort appears to have paid off: Crawford, an educator and political newcomer, is projected to win, according to the Associated Press. He leads the 19-term congresswoman 70-30 with 64 percent of the vote reporting.

—Mary Radcliffe, 538