Senator Bill Cassidy of Louisiana was defeated in the Republican primary on Saturday by Representative Julia Letlow, marking a significant upset in the state's newly implemented closed primary system.

Senator John Kennedy attributed Letlow's victory to former President Donald Trump's endorsement, stating that Trump's support had a "huge impact" on the race outcome. The endorsement came as Trump continues to target political rivals ahead of the midterm elections.

Cassidy's relationship with Trump became strained after the senator voted to convict the former president following the January 6, 2021, Capitol events. This vote was part of a broader pattern of disagreements between Cassidy and Trump that developed over recent years.

Former Senator Mitt Romney of Utah characterized Cassidy's defeat as a "loss for the country," commenting on the results Sunday. The primary was conducted under Louisiana's newly adopted closed primary system, which differs from the state's previous open primary format.

The Louisiana race is part of a broader pattern of Trump-endorsed challenges to Republican incumbents who have opposed the former president. Additional primary contests are scheduled for this week as the midterm election cycle continues.