Former President Donald Trump's influence within the Republican party and the potency of his endorsements are set for another evaluation on Saturday, as Louisiana holds primary runoff elections for a U.S. Senate seat.
Republican voters in the state will choose between U.S. Representative Julia Letlow and state Treasurer John Fleming for the open seat. This contest follows six weeks after incumbent Sen. Bill Cassidy, a Republican targeted by Trump, failed to secure a third term.
A victory for Letlow, who received Trump's endorsement prior to entering the race in January, would represent another success for Trump in his effort to populate Congress with loyal lawmakers. However, a win for Fleming would mark the third significant endorsement setback for Trump in this spring's Republican primaries.
In the initial primary, Letlow secured approximately 45% of the vote. Fleming garnered around 28%, and Cassidy received just under 25%. As no candidate reached the 50% threshold, Letlow and Fleming advanced to the runoff. Cassidy's defeat marked the first time an elected Republican senator lost renomination since Indiana's Richard Lugar in 2012.
Following Cassidy's concession, Trump commented on social media, stating that it was "nice to see that his political career is OVER!". Cassidy, in his speech to supporters, made a veiled reference to Trump's post-election rhetoric, saying, "When you participate in democracy, sometimes it doesn't turn out the way you want it to. But you don't pout, you don't whine. You don't claim the election was stolen… You don't manufacture some excuse."
Letlow, who also has the backing of Louisiana Gov. Jeff Landry, a prominent Trump ally, first won her congressional seat in 2021. She has consistently emphasized Trump's support throughout her Senate campaign. Fleming previously served eight years in Congress and was a White House deputy chief of staff during Trump's first term. He has positioned himself as the most conservative candidate in the Republican primary.
The Republican nominee is expected to be the clear frontrunner in the general election against either Democratic candidate Jamie Davis or Gary Crockett.
Trump's endorsement strength has been evident in several GOP primaries over the past two months, with his supported candidates unseating incumbents he opposed in races in Indiana, Kentucky, and Texas, in addition to the Louisiana primary.
However, Trump's endorsement streak in statewide and congressional Republican primaries was recently broken when his late endorsement of Rep. Randy Feenstra in Iowa's gubernatorial race was insufficient to secure victory for the congressman. Feenstra was narrowly defeated by Zach Lahn, who was supported by groups aligned with Trump's former Health Secretary Robert F. Kennedy Jr. and Turning Point USA.
Trump saw a rebound in South Carolina three weeks ago, where his endorsed candidates, Lt. Gov. Pam Evette for governor and Sen. Lindsey Graham for Senate, performed strongly in their respective primaries.
Two weeks prior, Trump-backed candidates won two of the three top races in Georgia and Alabama. The exception was in Georgia's gubernatorial runoff, where billionaire businessman Rick Jackson, running as an outsider, defeated the Trump-endorsed Lt. Gov. Burt Jones.
In Alabama's GOP Senate runoff, Rep. Barry Moore, a Trump supporter, comfortably defeated his rival Jared Hudson. In Georgia's Republican Senate runoff, Trump's endorsement aided Rep. Mike Collins in his victory over former college football coach Derek Dooley.
On Tuesday, Trump-backed candidate Anthony Constantino won a New York congressional race.
Letlow has stated that Trump's endorsement "means everything in this race."
Sen. Bill Cassidy of Louisiana fist bumps a supporter during a campaign stop on May 15, 2026.
President Donald Trump stands with Rep. Julia Letlow during the Congressional Ball at the White House Grand Foyer in Washington, D.C., on Dec. 11, 2025.
