President Donald Trump has intensified efforts to purge critics from the Republican Party by backing primary challengers in several high-profile races this month.

In Indiana, Trump targeted seven state senators who voted against his push to redraw congressional maps in a way that would help Republicans gain House seats in the November midterms. The lawmakers rejected the plan in December 2025 despite lobbying from Trump, Vice President JD Vance, and White House invitations. Trump endorsed opponents, including Tracey Powell against Sen. Jim Buck, whom he called a "pathetic RINO incumbent," and state Rep. Michelle Davis against Sen. Greg Walker. Outside groups aligned with Trump have spent over $6 million on ads attacking the incumbents, with primaries set for Tuesday.

Kentucky Rep. Thomas Massie faces one of the most aggressive challenges. Trump labeled Massie "the Worst 'Republican' Congressman we have had in many years" and a "Weak and Pathetic RINO" on Truth Social for opposing tax cuts, spending bills, foreign policy moves in Venezuela, and the release of Jeffrey Epstein files. Trump recruited and endorsed former Navy SEAL Ed Gallrein during an Oval Office meeting, telling him, "I needed him to run. Super PACs like MAGA KY and the Republican Jewish Coalition have poured more than $7 million into ads against Massie ahead of the May 19 primary.

In Louisiana, Trump endorsed Rep. Julia Letlow to challenge Sen. Bill Cassidy, who voted to convict him in the 2021 impeachment trial over the January 6 Capitol riot. Trump called Letlow a "Highly Respected America First Congresswoman" and urged her to run. The Senate primary is scheduled for May 16, with a potential runoff on June 27 if no candidate wins a majority.

Trump also reshaped the open Kentucky Senate race to replace retiring Senate Minority Leader Mitch McConnell. On Friday, he endorsed Rep. Andy Barr and offered a job as ambassador to rival Nate Morris, a Vance ally, to clear the field. Trump said Barr is the only candidate positioned to defeat the Democrats decisively in November. The primary is May 19, with other contenders including former Attorney General Daniel Cameron.

Trump's moves extend beyond these races. He criticized Maine Sen. Susan Collins and others for votes limiting his military authority in Venezuela, warning they "should never be elected to office again." A Trump adviser emphasized the message: "The president and many people around him have been very clear about what happens to those who do not stand up for his agenda."

The president's interventions have created a chilling effect among Republicans. Massie noted colleagues confide they avoid certain fights to dodge primaries, saying, "If I win, it means we have a legislative branch again that can function independently." GOP strategists worry resources spent defending safe seats will divert from battlegrounds, especially amid economic pressures and the ongoing conflict with Iran.

Trump's endorsements have proven influential in past primaries, with high win rates, though challengers continue entering races despite his support for incumbents elsewhere. Outcomes in these May contests will test his grip on the party as Republicans defend narrow majorities ahead of the midterms.