Letlow, who was endorsed by Trump, defeated state Treasurer John Fleming in the two-candidate runoff after they finished ahead of Cassidy in the GOP primary May 16.
Letlow pledged her loyalty to Trump in a race where Cassidy, who voted to convict the president 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.
“I am so filled with gratitude for the greatest president this country has every had, Donald J. Trump,” Letlow told supporters at her election night watch party in Baton Rouge. “I am also so incredibly grateful for your endorsement.”
Letlow’s victory caps Trump’s early 2026 effort to back Republican challengers to GOP lawmakers who have disagreed with him and replace them with ones more loyal. Kentucky Rep. Thomas Massie, Texas Sen. John Cornyn and five Indiana state senators all lost reelection bids last month to GOP challengers he endorsed.
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.
Letlow is now the immediate favorite to succeed Cassidy in a state Trump carried in 2024 by 22 percentage points. Letlow would become Louisiana’s first female Republican senator if elected.
Her supporters cheered as she stepped to the stage in Baton Rouge. One attendee let out a shriek a few minutes earlier after seeing on TV that The Associated Press had called the race.
Letlow 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.
It was Gov. Jeff Landry, whom Letlow also thanked, who began advocating for her to Trump last year. The president took until January to endorse her, however, making his announcement before she declared her candidacy.
She finished first in last month's voting with nearly 45%, compared with about 28% for Fleming and nearly 25% for Cassidy. Letlow and Fleming advanced to Saturday’s runoff because nobody won a majority that day.
For some voters, 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.”
