Washington — Louisianans are voting Saturday in the state's Republican Senate runoff, as two candidates vie to replace Sen. Bill Cassidy, who did not receive enough votes in the primary to advance.  

Rep. Julia Letlow and Louisiana state Treasurer John Fleming are facing off in the runoff, after no candidate secured 50% of the vote in last month's primary. At the time, Letlow came in first with more than 44% of the vote, while Fleming secured 28%. Cassidy, the GOP incumbent, came in third. 

President Trump encouraged Letlow to challenge Cassidy for the seat earlier this year after Cassidy had occasionally clashed with the administration, most notably with his vote to convict Mr. Trump in his impeachment trial after the Jan. 6 attack on the Capitol in 2021. Cassidy, a medical doctor, had also been at odds with the administration over HHS Secretary Robert F. Kennedy Jr.'s leadership, despite delivering the key vote to advance Kennedy's nomination last year. 

Cassidy's loss represented a key test of the power of the president's endorsement, which also preceded Sen. John Cornyn's primary loss in Texas a few weeks later. Since losing his primary, the Louisiana Republican has appeared more willing to break with the White House, and sparred with the president at a Senate Republican lunch meeting in recent days.

Ahead of the primary, Mr. Trump called Cassidy a "disloyal disaster" and endorsed Letlow, whom he called a "winner who will NEVER let you down."

Letlow, 45, has represented Louisiana in the House since 2021, when she became the first Republican woman from the state to be elected to Congress. Fleming worked in the first Trump administration and also represented Louisiana in the House from 2009 to 2017.

The winner of Saturday's runoff will likely be on a glidepath to the Senate. Louisiana is a solidly red state where Mr. Trump won 60% of the vote in 2024. The state last elected a Democrat to the Senate in 2008.