Trump backs Julia Letlow in Louisiana, igniting a Republican intra-party fight against Sen. Bill Cassidy

Donald Trump endorsed Congresswoman Julia Letlow for election to the Senate in Louisiana. The seat is currently held by Republican Bill Cassidy, who is seeking re-election and has clashed with the president repeatedly. Letlow has not yet formally entered the race and is expected to announce her decision in the coming weeks. The primary will take place next March 16 and, if confirmed, would be one of the strongest matchups of the 2026 election cycle.

"I know Julia well, have seen her tested at the highest and most difficult levels, and she is a TOTAL WINNER! A Proud Mother of two children, Julia is a wonderful person, has ALWAYS delivered for Louisiana, and would continue doing so in the United States Senate," Trump posted on his Truth Social account.

The president's preemptive endorsement is expected to incentivize Letlow to enter the race. The congresswoman left the door open in her response to the endorsement, "I’m honored to have President Trump’s endorsement and trust. My mission is clear: to ensure the nation our children inherit is safer and stronger."

"This United States Senate seat belongs to the people of Louisiana, because we deserve conservative leadership that will not waver," the congresswoman added.

Letlow was the wife of Luke Letlow, who won a House seat in 2020 but died before taking office. She then ran in the 2021 special election and won her husband's seat. She won handily and has since become a prominent Trump ally in the House.

Cassidy's response: "I am confident I will win"

Just hours after Trump endorsed Letlow, the senator responded, noting that he is confident of winning a potential showdown.

"I'm proudly running for re-election as a principled conservative who gets things done for the people of Louisiana. If Congresswoman Letlow decides to run I am confident I will win," he expressed on X.

The incumbent Republican senator was initially elected in 2014 and then re-elected in 2020. He is one of the few physicians in the Senate and currently chairs the Health, Education, Labor and Pensions Committee. However, the relationship with the president has not been the best. Despite backing much of his agenda between 2017 and 2021, he was one of the seven Republican senators who voted to convict Trump in the second impeachment attempt. In addition, Cassidy repeatedly attacked Trump ahead of the 2024 presidential election, questioning his leadership.

While things between the two seemed calmer since Cassidy voted to confirm Robert Kennedy Jr. as secretary of Health and Human Services, the senator again criticized the White House for changes to childhood vaccination recommendations.

Trump's decision pits him against the Senate Republican leadership. John Thune, the Republican majority leader in the Senate, already endorsed Cassidy and even campaigned with him in Baton Rouge. The incumbent also has the backing of Tim Scott of South Carolina, the chairman of the National Republican Senatorial Committee (NRSC), which is charged with electing more Republicans to the Senate.

Currently, the only big-name challenger to Cassidy is John Fleming, a former congressman and current Louisiana treasurer.