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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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


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


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


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


Voters in California’s 20th District may decide McCarthy’s successor today

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