BATON ROUGE — U.S. Rep. Julia Letlow won Louisiana’s Republican nomination for U.S. Senate on Saturday, delivering another win for President Donald Trump, whose effort to replace Republicans who crossed him was central to the race.

Letlow, whom Trump endorsed before she entered the race in January, defeated state Treasurer John Fleming in a runoff after the two finished ahead of Sen. Bill Cassidy in the GOP primary May 16.

In the Democratic primary, Jamie Davis, a northeast Louisiana crop farmer, defeated Gary Crockett, a Navy veteran and business executive. Both promoted addressing the cost of living and protecting social safety nets.

Letlow and Davis will square off in November. 

Letlow pledged her loyalty to Trump in a race where Cassidy, who voted to convict Trump on impeachment charges in 2021, spent a year working to keep Trump from going after him. She has promised to work in lockstep with Trump to advance his agenda.

Letlow’s victory caps Trump’s primary efforts to unseat Republicans he is unhappy with. Kentucky Rep. Thomas Massie, Texas Sen. John Cornyn and five Indiana state senators all lost reelection bids last month to challengers he backed.

However, Trump-backed candidates lost in two June GOP gubernatorial primaries: Rep. Randy Feenstra on June 2 in Iowa, to businessperson Zach Lahn; and Lt. Gov. Burt Jones of Georgia on June 16, to billionaire Rick Jackson. Both winners were outsiders competing with establishment favorites.

By winning Saturday, Letlow is the immediate favorite to succeed Cassidy in a state Trump carried in 2024 by 22 percentage points. Letlow also would become Louisiana’s first female Republican senator if elected.

Her supporters were awaiting her appearance at an event in Baton Rouge. One guest let out a shriek after seeing on TV that The Associated Press had called the race, as pop music pulsed in the background.

Letlow, a former college administrator and ardent Trump supporter, has been in the House since 2021. Her husband, Luke Letlow, died from COVID-19 complications after being elected to Congress in 2020, and she won a special election to fill the seat.

She finished first in last month's voting with nearly 45 percent of the vote, compared with about 28 percent for Fleming and nearly 25 percent for Cassidy.

“We have a chance to send a clear message that Louisiana stands with President Trump,” Letlow said Thursday in an online rally with the president. “He endorsed me because he knows I will stand with him.”

For some, Trump's endorsement was all that mattered.

“Trump’s lady all the way,” said Barbara Dufrene, 67, of Marrero. She added that she knew little about Letlow but was counting on the president to lower her healthcare costs and increase her social safety net. “I always vote whatever Trump wants.”

Letlow's success on May 16, campaign spending on her behalf and support from prominent Republicans had her well-positioned in the runoff. She was also endorsed by Gov. Jeff Landry, who consulted with Trump last year about her running for Senate, and U.S. House Majority Leader Steve Scalise.

Last month, Letlow won in parishes from the state's rural north to the New Orleans area in the southeast. She carried six of the 13 parishes that Fleming formerly represented in the U.S. House, including Caddo Parish, which includes Shreveport.

Fleming, a founder of the conservative House Freedom Caucus while in Congress, later worked in Trump's first administration. He reminded voters that he did not resign after the Jan. 6, 2021, attack on the U.S. Capitol by Trump supporters.

He directed his appeals to those who identify most closely with the president's “Make America Great Again” movement, saying his voting record is more conservative than Letlow's. His campaign ads describe him as MAGA “long before it was cool.”

Fleming told voters he was blocked from reaching Trump to seek his endorsement by White House allies of Landry. Fleming said he finally got on the phone with Trump and reminded the president who he was.

“I said nobody has been more loyal to you than me,” Fleming recounted during a June campaign stop. “He said, 'You’re fantastic! Why didn't you call?'”

The two campaigns spent comparably on advertising, roughly $1 million each, since the May 16 primary. But a super PAC that supports Letlow led all spending, accounting for $4.1 million in the past six weeks, according to the ad-tracking firm AdImpact.

Fleming had ads highlighting Letlow's previous public support for diversity, equity and inclusion policy, which Trump has tried to eliminate. Letlow, a former college administrator, said she supported DEI while interviewing for the position of president of the University of Louisiana-Monroe in 2020, but said this year she opposes it.

Fleming reposted an AI-generated video on the social platform X this month that purported to show Letlow saying she supported DEI because she “didn't know any better.” The fake image of Letlow also referenced her husband.

Fleming said he did not create the video “but it’s getting passed around Louisiana for a reason.”

Letlow condemned the sharing of the video as “disgraceful and indefensible,” chiefly for its mention of her late husband.

Letlow emphasized key priorities for social conservatives, notably her support for national legislation barring transgender women and girls from competing in school sports.

Fleming staked much of his campaign on opposition to carbon capture and sequestration, the process for injecting carbon dioxide waste underground to reduce industrial pollution. The technology’s build-out, including planned pipelines, has sparked backlash in rural Louisiana communities and divided the state GOP.

Fleming said such projects infringe on private property rights, and says federal government subsidies for the technology are wasteful.