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

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

Last Updated: March 19, 2024, 5:29 PM EDT

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.

Latest headlines:

Here's how the news is developing.
G. Elliott Morris Image
Mar 19, 2024, 9:10 PM EDT

Democrats get their man in Ohio's GOP Senate primary

Democrats are likely to be pleased with the Moreno win in the GOP primary for Ohio's Senate seat tonight. Because of his ideological extremity and endorsement from Trump, most Democratic strategists and political prognosticators believe him to be a weaker general-election candidate than his competitors would have been. Indeed, Democrats even took out ads in favor of Moreno, trying to boost him to exactly this outcome.

This is not a completely baseless idea. After the 2022 midterms, I found that GOP primary candidates who were endorsed by Trump went on to lag the predictions for general-election Democratic by a vote margin of about 5 percentage points. That large of an effect could tip a close race in Ohio, so the expected vote calculus likely favors Democrats here.

But the political calculus is another matter. Democrats have been criticized in the past for endorsing Trump's chosen candidates as an electoral strategy on the grounds that it increases the likelihood of Washington passing Republican policies and pushing Trump's agenda. Given that the Senate is likely to go Republican in the fall, having Trump-endorsed Moreno in the halls of Congress may provide a higher ROI for Trump than having a Senator Dolan or LaRose. By pushing these ads, Democrats are betting the return on votes will outweigh the potential downside. That bet does not come without risk.

—G. Elliott Morris, 538

Mar 19, 2024, 8:59 PM EDT

Haley picks up at least one Ohio county

With 35 percent of the expected vote counted in the Republican presidential primary in Ohio, Nikki Haley looks to have won at least one county, according to the Associated Press. She leads 58-34 in Holmes County with over 95 percent of the expected vote counted. Notably, Holmes County has the largest Amish population in the country, with 48 percent of county residents identifying as Amish, per the U.S. Census.

—Mary Radcliffe, 538

Mar 19, 2024, 8:57 PM EDT

Chicago's homelessness referendum is trailing

With 32 percent of the expected vote in, the Chicago referendum that would raise some transfer taxes on property over $1 million to pay for homelessness initiatives is losing 44 to 56 percent, according to the Associated Press. The referendum is supported by progressives like Mayor Brandon Johnson, who say that the measure is needed to reduce the rising cost of housing in the city. But it's opposed by those who are worried that the property market is still too fragile after the COVID-19 pandemic. The referendum would increase transfer taxes on properties over $1 million, while decreasing those same taxes on properties worth less than that. The increased revenue would be used to fund homelessness services in a city that has struggled to house all of its residents in recent years.

—Cooper Burton, 538

Supporters of a Chicago ballot measure that raises a one-time tax on luxury properties to fund services for homeless people rally prior to a court hearing, Feb. 14, 2024, in Chicago.
Charles Rex Arbogast/AP
Jacob Rubashkin Image
Mar 19, 2024, 8:53 PM EDT

ABC projects Moreno to win

ABC News has projected Moreno will win the GOP primary for Senate in Ohio, setting up a clash with three-term incumbent Sherrod Brown this fall. Moreno was endorsed by Trump, but also benefitted from spending by a Democratic super PAC that viewed him as a weaker general election opponent than the man he beat, state Sen. Matt Dolan.

—Jacob Rubashkin, Inside Elections

Cleveland businessman and Republican Senate candidate Bernie Moreno speaks at a rally, Mar. 16, 2024, in Vandalia, Ohio.
Jeff Dean/AP

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