Incumbent Republican Sen. Bill Cassidy, first elected in 2014, is seeking a third term in 2026, but not without facing a primary challenge. Cassidy has drawn significant attention within the Republican Party for his vocal criticism of former President Donald Trump. He voted to convict Trump during his second impeachment trial, a decision that led the Republican Party of Louisiana to formally censure him. State Treasurer John Fleming and State Senator Blake Miguez have entered the primary against Cassidy, while Congresswoman Julia Letlow has expressed interest in joining the race. Former Democratic Governor John Bel Edwards declined to run, leaving Democrats without a major candidate and positioning the eventual Republican nominee as the clear favorite.

Louisiana’s election system is unique in that a runoff will be held on December 12 if no candidate secures a majority in the November vote. In the 2024 presidential election, Donald Trump carried Louisiana by 22 points, extending the state’s streak of double-digit Republican victories in every presidential contest since 2004.