Rep. Julia Letlow (R-La.) won a Republican primary runoff for Senate in Louisiana on June 27, beating state Treasurer John Fleming.

Letlow is now the immediate favorite to succeed Cassidy in a state Trump carried in 2024 by 22 percentage points.

She will face the Democratic candidate for senator, Jamie Davis, in the Nov. 3 general election, and would become Louisiana’s first female Republican senator if elected.

“I am deeply honored by the trust the people of Louisiana have placed in me,” Letlow wrote in a post on X. She had been endorsed by President Donald Trump.

“Thank you to every voter, volunteer, and supporter who made this victory possible. I am grateful for President Trump’s endorsement, and the support of Governor Landry, Leader Scalise, Congressman Higgins, Attorney General Murrill, and so many more incredible conservatives who came together to make tonight possible.”

The race went to a runoff because none of the Republican candidates won a majority in the May 16 primary. Sen. Bill Cassidy, the incumbent, finished third in the primary and didn’t qualify for the runoff.

Cassidy was one of seven Republican senators who voted to convict Trump during the president’s second impeachment trial in February 2021, saying that Trump was guilty of being involved in the Jan. 6 Capitol breach. The vote triggered an immediate backlash from many Republicans. The Louisiana Republican Party voted to censure Cassidy.

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.