Trump's grip over GOP tested as state senators who defied president challenged in key primaries

It's primary day in Republican-dominated Indiana, where President Donald Trump’s immense sway over the GOP is on the line, as his endorsements in key races will be tested.

In neighboring Ohio, another right-leaning state, some of Tuesday's top primaries will tee up crucial general election showdowns in November’s midterm elections, when Republicans will be defending their slim Senate and razor-thin House majorities.

Two congressional incumbents in Indiana — Republican Rep. Jim Baird and Democratic Rep. Andre Carson — face serious primary challenges.

And in Ohio, Republicans will pick from a crowded primary field in the race to face off with vulnerable Democratic Rep. Marcy Kaptur.

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Five months ago, Republicans in the GOP-dominated Indiana state Senate withstood immense pressure from Trump and his allies and voted down congressional redistricting, which would have given solidly red Indiana two more right-leaning U.S. House seats ahead of the midterms.

Fast-forward to today, and eight of those state senators are facing GOP primary challenges. Seeking retribution, the president endorsed challengers to seven of the eight Republican lawmakers who voted against the redistricting bill.

The president’s allies have shelled out more than $6 million to try to oust the state senators, according to the national ad tracking firm AdImpact. Among those in the political fight on behalf of the president are two national groups: Turning Point USA’s political wing and the Club for Growth. Also leading the charge are Hoosier Leadership for America and American Leadership PAC, which are aligned with GOP Sen. Jim Banks, a top Senate ally of the president. Groups allied with Republican Gov. Mike Braun are also part of the full court press.

The intra-party battle is seen not just as a test of fealty to Trump but rather a fight between MAGA forces and more traditional conservatives for the future of the GOP.

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"We’ve got to change those old-style Republicans, put in people who will fight, fight against the Democrat gerrymandering," Club for Growth President David McIntosh told Fox News Digital.

McIntosh, a former congressman from Indiana, said, "I want to see my state do the right thing."

But the besieged incumbents have significantly outraised their challengers, and have also been boosted by the Indiana Senate GOP caucus.

In an interesting side note, one of the races pits Trump versus his former Vice President Mike Pence.

Trump is backing challenger Tracey Powell, who is trying to take out state Sen. Jim Buck, who's backed by Pence, a former Indiana governor and congressman.

A pro-Trump source involved in the Indiana showdowns told Fox News Digital that a victory would be considered winning half the seats, and anything beyond that would be a major win.

In western Indiana's 4th Congressional District, the Trump-backed Baird is being challenged by state Rep. Craig Haggard. And in Indiana's 7th Congressional District, Carson is facing three primary challenges, including Georgie Hornedo, a veteran of former President Barack Obama's administration.

Vivek Ramaswamy grabbed national attention when he ran for the 2024 GOP presidential nomination before dropping out and becoming a top Trump surrogate.

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Now, the multimillionaire biotech entrepreneur and business leader is all but certain to capture the Republican gubernatorial nomination in his home state of Ohio.

Ramaswamy, who is backed by Trump, will face off in November against Dr. Amy Acton, a doctor and researcher who served as director of the state Department of Health from 2019 to 2020. Acton is unopposed in the Democratic primary.

The winner will succeed term-limited GOP Gov. Mike DeWine.

It’s a similar story in Ohio’s Senate primary, where appointed Republican Sen. Jon Husted, a former lieutenant governor, is unopposed in the GOP primary.

Former longtime Democratic Sen. Sherrod Brown is expected to cruise to his party’s nomination.

The winner will serve the final two years of the term of Vice President JD Vance, who stepped down from the Senate after the Trump-Vance ticket won the 2024 presidential election.

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Once a top general election battleground state, Ohio has shifted to the right over the past decade, with Trump carrying the state by 11 points in the 2024 election. But this year's races for the Senate and governor are expected to be very competitive. And the Senate race is one of a handful across the country that may determine if the GOP holds the majority or if the Democrats flip the chamber.

In northwest Ohio's 9th Congressional District, the 79-year-old Kaptur, who is already the longest serving woman in U.S. House history, is running for a 23rd two-year term.

But Kaptur, who barely won re-election in 2024, is now running in a district that's even redder than it was two years ago, thanks to Republican-steered mid-decade redistricting.

Top non-partisan political handicappers The Cook Political Report, Inside Elections, and Sabato's Crystal Ball give the GOP a slight edge in the general election showdown.

The packed field of GOP contenders fighting to take on Kaptur in November include former state Rep. Derek Merrin, who lost to the congresswoman by a razor-thin margin two years ago, former state Rep. Josh Williams, Air Force veteran Alea Nadeem, and former ICE Deputy Director Madison Sheahan.

Republicans will also choose a nominee in the Cincinnati-based 1st District, where Democratic Rep. Greg Landsman is running for re-election.

Democrats will nominate a candidate in Ohio's 15th Congressional District, south and west of Columbus, where they hope to take out Republican Rep. Mike Carey in November.