Rep. Julia Letlow (R-LA) is officially challenging incumbent Republican Sen. Bill Cassidy. According to Fox News, the 44-year-old House Republican declared her candidacy at a “closed-door business breakfast in Baton Rouge” on Tuesday. Letlow’s candidacy follows President Trump endorsing her over Cassidy. “Today, I am announcing my candidacy for the United States Senate to ensure the nation we leave our children is safer and stronger. Louisiana deserves a conservative Senator who will not waver. I am honored to have President Trump’s endorsement and trust. Let’s Geaux!” Letlow wrote on social media Tuesday. Watch her campaign announcement video below: Today, I am announcing my candidacy for the United States Senate to ensure the nation we leave our children is safer and stronger. Louisiana deserves a conservative Senator who will not waver. I am honored to have President Trump’s endorsement and trust. Let’s Geaux! pic.twitter.com/4Xm7hzdro7 — Julia B Letlow, Ph.D. (@jbletlow) January 20, 2026 Fox News has more: Trump’s support of Letlow, who was elected in 2021 after her husband Luke died from COVID shortly before taking office in the House, is a serious setback for Cassidy, a physician and chair of the powerful Senate Health committee who is running for a third six-year term in the solidly red state. “Congresswoman Letlow called me this morning to say she was running. She said she respected me and that I had done a good job,” Cassidy said in a statement after Letlow’s announcement. “I will continue to do a good job when I win re-election. I am a conservative who wakes up every morning thinking about how to make Louisiana and the United States a better place to live.” Trump’s endorsement of Cassidy’s challenger creates a major political headache for Senate Majority Leader John Thune, who is backing Cassidy and teamed up with the senator last week in Louisiana. Trump upended an already crowded GOP Senate primary in Louisiana on Saturday night, with a social media post making it clear that if the 44-year-old Letlow launched a Senate campaign, she’d have his backing. “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,” Letlow said after receiving Trump’s 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. ⁰This United States Senate seat belongs to the people of Louisiana, because we deserve conservative leadership that will not waver. pic.twitter.com/851hQkXhIN — Julia B Letlow, Ph.D. (@jbletlow) January 18, 2026 The New York Post shared further: Cassidy, who chairs the influential Senate Health, Education, Labor and Pensions (HELP) Committee, had been spared a tough challenge from popular ex-Louisiana Gov. John Bel Edwards, a Democrat, last year. He still has supported the president on critical votes concerning executive war powers resolutions and measures to rein in tariffs. But his opposition at times to Trump’s appointees — like Health and Human Services Secretary Robert F. Kennedy Jr. — and record of voting against the president has rankled some in the GOP. After the Jan. 6, 2021, Capitol riot, Cassidy was one of seven Senate Republicans who voted to convict Trump after he was impeached by House Democrats. The Louisiana Republican had also called on the 45th president to drop out of the 2024 election following the unsealing of the classified documents indictment.