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.
Mar 19, 2024, 7:37 PM EDT

Polls are now closed in Ohio!

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

Nathaniel Rakich Image
Mar 19, 2024, 7:28 PM EDT

A quiet but consequential primary in Ohio's 13th

Rounding out our key House races in Ohio as polls close at 7:30, the Republican primary has been pretty uneventful in another Ohio swing seat: the 13th District, which Biden would have carried by 3 percentage points in 2020. Democratic Rep. Emilia Sykes will likely face either former state Sen. Kevin Coughlin or Hudson City Councilor Chris Banweg in November. Not much distinguishes the two, though: They both support Trump and share the same conservative positions on abortion, immigration, guns and more. And they both have raised only modest amounts of money: $332,000 for Coughlin, $280,000 for Banweg. Sykes, by contrast, has pulled in $1.9 million for her reelection bid so far.

—Nathaniel Rakich, 538

A view shows a polling place sign as the Democratic and Republican parties hold primary elections in Dayton, Ohio, Mar. 19, 2024.
Megan Jelinger/Reuters

Nathaniel Rakich Image
Mar 19, 2024, 7:22 PM EDT

Will Trump's endorsees win today?

Trump has endorsed only three candidates in seriously contested primaries today: Moreno, Bost and Merrin. With all three locked in competitive races, tonight's results could be a good signal of whether Trump's endorsement is as powerful as it used to be. We'll be tracking these races throughout the night.

—Nathaniel Rakich, 538

Nathaniel Rakich Image
Mar 19, 2024, 7:16 PM EDT

The GOP primary in Ohio's 9th is a mess, again

One of today's most consequential primaries for the general election is taking place in Ohio's 9th District. According to Daily Kos Elections, Trump would have carried the district 51 percent to 48 percent in 2020. But in 2022, incumbent Democratic Rep. Marcy Kaptur defeated Republican Air Force veteran J.R. Majewski 57 percent to 43 percent here thanks to Majewski's weaknesses as a candidate: He exaggerated his military service, attended the Jan. 6 rally (though he says he didn't enter the Capitol) and once subscribed to the QAnon conspiracy theory.

Majewski quickly announced he would run again in 2024, agitating Republican operatives who feared he would once again throw away a winnable House seat. But to their relief, he withdrew from the race a few weeks ago, leaving the primary to state Rep. Derek Merrin and former state Rep. Craig Riedel. Riedel was originally the top alternative to Majewski, but a couple of his pro-Trump supporters withdrew their endorsement of him after audio leaked of him calling Trump "arrogant." That sent GOP elders scrambling to find a new alternative to Majewski, and Merrin — who was in line to be the speaker of the Ohio state House last year until a faction of renegade Republicans joined Democrats to elect a different Republican — jumped into the race just before the filing deadline.

The primary is far from settled, though. While Trump endorsed Merrin just yesterday, and Speaker Mike Johnson endorsed Merrin in January, many establishment Republicans, such as House Majority Leader Steve Scalise and Majority Whip Tom Emmer, are still with Riedel. And Merrin's late entry into the race means he trails Riedel badly in fundraising, $175,000 to $1.2 million. And while he's no Majewski, a Riedel win could still give Republicans headaches: He's aligned with the tea party movement and has previously expressed interest in joining the hardline House Freedom Caucus.

—Nathaniel Rakich, 538

A voter casts their ballot as the Democratic and Republican parties hold primary elections in Dayton, Ohio, Mar. 19, 2024.
Megan Jelinger/Reuters

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