BATON ROUGE, La. (AP) — U.S. Rep. Julia Letlow advanced to a runoff in Louisiana’s Republican Senate primary Saturday, capitalizing on the power of President Donald Trump’s endorsement in another attempt to purge his party of people he views as disloyal. State Treasurer John Fleming came in second to join her in the next round of voting.

Trump supported Letlow over incumbent Sen. Bill Cassidy, one of the few Republican senators who voted to convict him during his second impeachment trial over the attack on the U.S. Capitol on Jan. 6, 2021. Cassidy, a doctor, has also clashed with Health Secretary Robert F. Kennedy Jr. over vaccine policy, though he provided crucial support to help Kennedy get confirmed.

“I want to say thank you to a very special man who you all know, the best president this country has ever had, President Donald Trump,” Letlow told supporters in the evening, flanked by her two young children. “There is no greater endorsement than the endorsement of President Trump. We’ll always be singing that from the mountaintops.”

Invoking Cassidy's impeachment vote, Letlow said: “Louisiana was not pleased with that vote. They took that as a sign that he had turned his back on the Louisiana voters.”

Trump, who has been trying to dislodge Cassidy, unloaded on him the morning of the election, calling him “a disloyal disaster” and “a terrible guy” on social media. In the evening he followed up with: “Congratulations to Congresswoman Julia Letlow on a fantastic race, beating an Incumbent Senator by Record Setting Numbers.”

Speaking to supporters after the result was known, Cassidy made a thinly veiled reference to the president, saying, “Insults only bother me if they come from somebody of character and integrity, and I find that people of character and integrity don’t spend their time attacking people on the internet.”

“Our country is not about one individual,” he said. “It is about the welfare of all Americans, and it is about our Constitution.”

The Louisiana primary comes in the middle of a month of campaigns by Trump to exact retribution on politicians who have crossed him. On May 5 he helped dislodge five of seven Indiana state senators who rejected his redistricting plan.

Next Tuesday, U.S. Rep. Thomas Massie of Kentucky will face a Trump-backed challenger, Ed Gallrein, in another Republican primary. Massie angered Trump by opposing his signature tax legislation over concerns about the national debt, pushing for the release of the Jeffrey Epstein files and opposing his decision to go to war with Iran.

By receiving less than 50% of the vote, Letlow and Fleming, a former U.S. House member and Trump administration official, were unable to avoid the runoff, which will take place June 27. The GOP winner will almost certainly take the November general election because of the state’s Republican leanings.

Jeanelle Chachere, a 66-year-old nurse, said she considers Cassidy “a phony” and voted for Letlow solely because Trump endorsed her.

“I’m going by what he says, because I like what he does,” she said.

Election changes stir concern

The election was scrambled by a recent U.S. Supreme Court decision gutting a part of the Voting Rights Act that affects how congressional maps are drawn. Although the Senate primary is moving forward, Louisiana leaders decided to delay House primaries until a future date to allow them to redo district lines ahead of time, a shift that threatened to cause confusion for voters on Saturday.

Mary-Patricia Wray, who has consulted for Republican and Democratic candidates in Louisiana, said the change could weigh against Cassidy by dampening turnout among voters who are less fervently pro-Trump.

“Suspending the congressional primaries hurts Cassidy,” she said. “Some people believe the Senate primary is canceled.”

Cassidy also complained that a new primary system enacted last year confused voters by requiring them to ask for a partisan ballot instead of the all-party primary previously in place. He said some called his office to say they had been unable to vote for him.

“The process that was set up was destined to be confusing,” Cassidy told reporters Friday.

Dadrius Lanus, executive director of the state Democratic Party, said his team fielded hundreds of calls from voters statewide who said the changes undermined their ability vote as they planned.

“A lot of the information should have gotten to voters well in advance,” Lanus said. “It’s literally been a whirlwind of confusion.”

Incumbent senator tried to hang on

Cassidy waged an aggressive campaign to convince voters he should not be counted out.

The senator's campaign was expected to have spent roughly $9.6 million on advertising through May 16, according to the ad-tracking firm AdImpact. And Louisiana Freedom Fund, a super PAC supporting him, was on track to spend $12.3 million.

By comparison Letlow’s campaign, which launched Jan. 20, spent roughly $3.9 million, while a super PAC backing her, the Accountability Project, spent about $6 million.

Fleming's campaign spent about $1.5 million.

Cassidy and Louisiana Freedom Fund ran ads attacking Letlow within days of her entering the race for supporting diversity, equity and inclusion initiatives, which Trump has tried to root out of the federal government.

Letlow, a college administrator before her election to the House, said she supported DEI while interviewing for the position of president of University of Louisiana-Monroe in 2020.

The ads, an attempt to characterize Letlow as a progressive trying to pass as a conservative, were one way Cassidy tried to flip the script in a race where he was on the outs with Trump.

Targeted by Trump

The senator's vote in favor of convicting the president after his 2021 impeachment has shadowed Cassidy throughout his second Senate term.

John Martin, a 68-year-old retired engineer in south Louisiana, said he would vote for Letlow because he was still upset by Cassidy's decision. He waved a flyer from Letlow’s campaign showing her standing alongside the president.

“I know a lot more about Cassidy than I do about her,” Martin said. “But if she’s endorsed by Trump, I’m going to believe that.”

Cassidy steered clear of Trump’s ire last year, supporting Kennedy to lead the Department of Health and Human Services despite his public reservations about the nominee’s anti-vaccine views.

As chair of the Senate health committee, Cassidy has been more publicly critical of Kennedy, including over funding cuts for vaccine development.

Trump blamed Cassidy for the failed nomination of his second choice for surgeon general, Casey Means, who raised doubts about vaccinating newborns for hepatitis B, a practice Cassidy supports. Trump withdrew the Means nomination and blasted Cassidy.

Letlow waited for Trump's backing

Letlow considered running last year but only entered the race after Trump announced his endorsement in January.

By that time Fleming, a former House member and Trump administration official who was elected state treasurer in 2023, was already in the race as a Trump devotee. But Landry was looking for a better-known challenger, and he suggested Letlow to the president.

Letlow had an unconventional and tragic entry into politics.

In 2020, while she was a college administrator, her husband Luke was elected to the U.S. House but died of COVID-19 before he could be sworn in. Letlow ran for and won the seat in a March 2021 special election and was reelected in 2022 and 2024.

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Beaumont reported from Des Moines, Iowa.

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