Sen. Bill Cassidy, the Louisiana Republican who voted to convict President Trump at his second impeachment trial, finished third in his own party's Senate primary on Saturday, ending his bid for a third term and sending Trump-backed Rep. Julia Letlow and state Treasurer John Fleming to a June 27 runoff.

The defeat makes Cassidy the first sitting Republican senator denied renomination since Indiana's Richard Lugar fell in 2012, and it hands Trump the most direct primary scalp of his second-term campaign to remove Republicans he views as disloyal. With 93 percent of the expected vote counted, Letlow led with 45 percent, Fleming had 28 percent and Cassidy trailed at 25 percent, according to NBC News.

The vote

Louisiana held its first Senate primary under a closed system enacted last year at the urging of Republican Gov. Jeff Landry, replacing the all-party jungle primary that had long protected Cassidy by allowing Democrats and independents to vote in his races. Only registered Republicans could cast a ballot Saturday. Landry, a Trump ally, endorsed Letlow and urged donors to back her.

Landry also postponed Louisiana's U.S. House primaries after a recent Supreme Court ruling on the state's congressional map. "Suspending the congressional primaries hurts Cassidy," Mary-Patricia Wray, a Louisiana consultant who has worked for candidates in both parties, told the Associated Press. "Some people believe the Senate primary is canceled."

Cassidy and an allied super PAC, Louisiana Freedom Fund, spent more than $20 million on advertising, according to the tracking firm AdImpact — more than Letlow and Fleming combined. Much of that money went to ads branding Letlow "Liberal Letlow" over her past support for diversity, equity and inclusion programs while she was a college administrator at the University of Louisiana at Monroe. Fleming, who has largely self-funded with $10.6 million in loans, made the same charge.

The impeachment shadow

Cassidy, a 68-year-old physician, was one of seven Senate Republicans who voted in February 2021 to convict Trump for his role in the Jan. 6 attack on the U.S. Capitol. Trump was acquitted, but the vote followed Cassidy through the rest of his second term and into this race. Trump endorsed Letlow in January and on the morning of the primary called Cassidy "a disloyal disaster" on Truth Social.

After the race was called, Trump returned to the platform to declare that Cassidy's "disloyalty to the man who got him elected is now a part of legend, and it’s nice to see that his political career is OVER!"

Cassidy, conceding from a Baton Rouge stage, did not name Trump but pointed at him. "When you participate in democracy, sometimes it doesn’t turn out the way you want it to. But you don’t pout, you don’t whine, you don’t claim the election was stolen, you don’t find a reason, you don’t manufacture some excuse," Cassidy said. "You thank the voters for the privilege of representing the state or the country for as long as you’ve had that privilege, and that’s what I’m doing right now."

The Kennedy front

A second grievance came from Health Secretary Robert F. Kennedy Jr. Cassidy supplied a deciding vote to confirm Kennedy in early 2025 despite public misgivings about Kennedy's record on vaccines, and as chairman of the Senate Health, Education, Labor and Pensions Committee has since broken with the secretary on vaccine policy, including a change to the hepatitis B schedule for newborns. Trump publicly blamed Cassidy for the failure of his second surgeon general nominee, Casey Means, a Kennedy ally, after Cassidy did not advance the nomination through committee. The Kennedy-aligned MAHA PAC put $1 million behind Letlow.

The runoff

Letlow, 45, won her House seat in a March 2021 special election after her husband, Luke Letlow, died of COVID-19 days after being elected. She is the first Republican woman elected to Congress from Louisiana. Fleming served in the U.S. House from 2009 to 2017, was a founding member of the House Freedom Caucus, worked as a deputy chief of staff in Trump's first White House and was elected state treasurer in 2023.

Fleming told NBC News that someone "around" the Trump administration had offered him a job to leave the race and clear a path for Letlow. The White House did not respond to NBC's request for comment. The Cook Political Report rates the Louisiana seat as solidly Republican; Trump carried the state by 22 points in 2024, and Louisiana has not elected a Democratic senator since 2008. Farmer Jamie Davis advanced from a Democratic primary that also went to a runoff.

The view from leadership

Not every Republican wanted this outcome. The National Republican Senatorial Committee, chaired by Sen. Tim Scott of South Carolina, had backed Cassidy, and Senate Majority Leader John Thune said Thursday that "Bill Cassidy has been a terrific senator for Louisiana." Some Louisiana voters interviewed at the polls said they valued Cassidy's willingness to break with his party. "It shows that he’s less influenced by a party, which I like," Donny Gutierrez told NBC News at a Baton Rouge polling place.

Trump's next test comes Tuesday in Kentucky, where Rep. Thomas Massie faces a Trump-backed primary challenger. A Trump political adviser told NBC News that the president and his team are more focused on Massie than they were on Cassidy, saying, "There is no way he views Cassidy and Massie the same."