The competitive Republican primary race for Louisiana Sen. Bill Cassidy’s seat is headed to a runoff election, The Associated Press called Saturday night—but Cassidy himself won’t be moving forward.

A challenger endorsed by President Donald Trump, Louisiana Rep. Julia Letlow, secured the largest share of the vote, according to the AP, underlining the President’s influence. State Treasurer John Fleming came in second.

As neither Letlow nor Fleming garnered more than 50% of the votes, they are now set to face off in a runoff next month. Cassidy's third-place finish, meanwhile, means the end of his bid for a third term in the Senate.

In an election night speech, Cassidy did not directly mention Trump, but appeared to allude to the President and, in particular, his false claims that the 2020 election was stolen from him.

"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 find a reason why you lost," the senator said. "You thank the voters for the privilege of representing the state or the country for as long as you’ve had that privilege, and that’s what I’m doing right now."

Trump congratulated Letlow on beating Cassidy in a post on Truth Social late Saturday.

"Julia Letlow is a fantastic person and, after taking care of some additional business, will make a brilliant Senator for the Great People of Louisiana, a State that I love, helped make prosperous with my Energy Policies and everything else, and won six times in a row, including Primaries," he wrote.

The primary battle has been rife with intra-party tension. While Senate Majority Leader John Thune and the National Republican Senatorial Committee backed Cassidy, other prominent Republican leaders including Trump and Louisiana Gov. Jeff Landry threw their support behind Letlow. In January, Trump announced his endorsement of Letlow before she had officially launched her campaign, calling her “a Great Star” who “has ALWAYS delivered for Louisiana.” While he didn’t mention Cassidy in the post, Trump’s endorsement of the sitting senator’s opponent was a clear snub. 

Dr. Silas Lee, a New Orleans-based pollster and professor at Xavier University of Louisiana, told TIME that Cassidy’s loss demonstrated that incumbency “is not the safety it once was,” and that anti-Trump Republican voters are a “fringe element” in the party. 

"Candidates who articulated their support for Trump's agenda did not experience defeat.  However, we must keep these results in context of the political and social environment in which they occur. Closed party primaries attract the ideologically aligned (usually conservative voters)." 

In the lead-up to the Saturday election, polling showed Cassidy trailing Letlow and, at times, Fleming.

Cassidy has long been a subject of the President’s ire. The Louisiana senator was among the seven Republicans who voted to convict Trump in his second impeachment trial back in 2021. Cassidy, a physician and proponent of vaccines, has also been one of few politicians within Trump’s party to push back against the changes the Administration has made to the nation’s vaccine policies. During the confirmation hearings for Robert F. Kennedy Jr., who is one of the country’s most notorious vaccine skeptics, as Secretary of Health and Human Services, Cassidy expressed concerns about Trump’s decision to nominate him for the role, though the Louisiana senator still ultimately voted to confirm him.

Cassidy and the President’s strained relationship came back into the spotlight last month, when Trump railed against the senator on Truth Social. In his post, the President accused Cassidy of having “stood in the way” of his controversial nominee for U.S. surgeon general, Casey Means. Trump withdrew Means’ name for consideration after her confirmation stalled because of lack of support.

“For months, Senator Bill Cassidy (of the GREAT State of Louisiana!), a very disloyal person whose ‘TRUMP’ Endorsement got him elected, but later voted to impeach ‘President Trump’ on what has now proven to be a total Hoax and Scam, has stood in the way of Robert F. Kennedy Jr.’s Nominee, Casey Means, for the important position of U.S. Surgeon General,” Trump said in the post.

Cassidy is one of several Republican lawmakers up for reelection this year who the President has publicly criticized and declined to endorse, choosing instead to back their primary challengers. 

While the balance of power in Washington is at stake in the upcoming November midterm elections, Cassidy’s seat is unlikely to flip; the Cook Political Report ranks it as “Solid Republican.”