The resounding defeat of Sen. Bill Cassidy (R) in Saturday’s Louisiana primary has sent shock waves through the Senate Republican Conference, underscoring how Republicans who look to distance themselves from President Trump and his low approval ratings will have to think twice about paying a political price for perceived disloyalty.

Cassidy’s ouster came a few weeks after Trump and his allies helped defeat five state senators in Indiana who defied Trump’s desire to redraw the state’s congressional map, sending a loud message to any Republican on Capitol Hill thinking about clashing with the president.

“It’s hard to confuse that message. The message is the one unifying principle of the Republican Party today is Donald Trump, and if you appear to abandon him, the party will abandon you,” said Vin Weber, a GOP strategist and former member of House Republican leadership.

Cassidy was viewed as an underdog in the Louisiana primary against Rep. Julia Letlow (R-La.), who was endorsed by Trump, but the fact that the two-term incumbent mustered only 25 percent of the vote and failed to make the June 27 runoff came as a shock to some of his Senate GOP colleagues. Former Rep. John Fleming (R-La.) came in second with 28 percent.

Senate Majority Leader John Thune (R-S.D.) offered a subdued response Monday afternoon when asked about Cassidy’s decisive defeat and praised his colleague.

“Bill Cassidy is a very principled conservative, very independent thinker and probably knew the challenges he was up against in that race. The way it turned out, obviously, the Republican voters of Louisiana have spoken, and so we’ll move on,” he said.

He said Cassidy “can be a real force for change and a factor in trying to get some things done,” noting that as Senate Health, Education, Labor and Pensions Committee chair, Cassidy heads “an incredibly significant and powerful committee here.”

Thune’s praise of Cassidy stood in stark contrast to Trump’s Sunday post on Truth Social rejoicing in the Louisiana senator’s defeat.

“His disloyalty to the man who got him elected is now a part of legend, and it’s nice to see that his political career is OVER!” Trump exulted on social media, citing Cassidy’s vote in 2021 to convict him on an impeachment charge of inciting an insurrection on Jan. 6 of that year.

Trump then quickly turned his sights on Rep. Thomas Massie (R-Ky.), who faces a tough primary battle against Ed Gallrein, a Trump-backed challenger, on Tuesday.

“The worst Congressman in the long and storied history of the Republican Party, is Thomas Massie. He is an obstructionist and a fool. Vote him out of office tomorrow, Tuesday,” Trump urged his supporters in a post Monday morning on Truth Social.

Massie is a seven-term House incumbent who has repeatedly defied Trump on major votes. He spearheaded Congress’s passage of the Epstein Files Transparency Act, which Trump initially opposed and then signed into law last year.

A major loyalty test for Senate Republicans will come later this week when they vote on a budget reconciliation package, which may include up to $1 billion in taxpayer funding for the new White House ballroom, one of Trump’s top priorities.

A handful of Republican senators have told Thune they don’t want to vote for the ballroom funding because they fear that steering taxpayer dollars toward a lavish ballroom — even if the funds are earmarked for security upgrades — will open them to future political attacks.

Sens. John Curtis (Utah), Rand Paul (Ky.), Susan Collins (Maine), Rick Scott (Fla.) and Thom Tillis (N.C.) are among the GOP lawmakers who have raised concerns about or objections to paying for the ballroom with taxpayer money.

But Trump has insisted that Senate GOP leaders find a way to authorize and fund the ballroom through legislation, which would help the White House get around a ruling from U.S. District Judge Richard Leon halting above-ground construction of the project until Congress approves it.

Tillis, an outspoken critic of some of the Trump administration’s actions this year, reacted angrily to Cassidy’s loss, sending an email to Republican colleagues on Monday threatening to block a budget reconciliation package from moving on the Senate floor later this week — even though it’s a top Trump priority.

Tillis expressed his disappointment over Cassidy’s loss on Saturday and urged Republican colleagues to delay action on the reconciliation bill so as not to force Sen. John Cornyn (Texas), another Republican colleague facing a tough primary on May 26, to stay in Washington until late this week to vote on the budget bill, according to a source familiar with the email’s details.

The North Carolina senator accused the White House of setting an “arbitrary” deadline of getting the bill done by June 1 and trying to rush it through Congress. He said that wouldn’t give Republican lawmakers enough time to work on the “major policy problem” posed by the White House “air dropping” language in the bill to authorize and fund the controversial ballroom.

Axios first reported that Tillis had vented his concerns about moving forward on the budget reconciliation package this week.

Senate Parliamentarian Elizabeth MacDonough handed Trump and Senate GOP leaders a setback over the weekend by ruling that the $1 billion in funding for the Secret Service to build security upgrades for the new 90,000-square-foot ballroom does not conform to the Senate’s Byrd Rule and therefore would not be eligible to pass the Senate with a simple-majority vote.

That ruling sets up the ballroom provision to be struck from the bill, but Thune on Monday said GOP leadership will work on revising the language until it meets with the parliamentarian’s approval and can be included in the package along with $70 billion in funding for immigration enforcement operations.

“I don’t think it should come as any surprise there’s feedback and this idea doesn’t work because it doesn’t fit within the parameters of … the restrictions the Byrd [Rule] requires you to meet,” Thune said, downplaying the notion that the parliamentarian’s ruling killed the authorization and funding of the ballroom.

“You try another approach. There was one issue last summer in reconciliation where we landed it on the fifth try. So you just kind of continue to figure out how do we address the concerns that are addressed there and look at a pathway to do that,” he said.

Thune acknowledged Tillis’s threat to block the bill from advancing in the wake of Cassidy’s loss but argued that Republican senators should act quickly and pass the bill before the Memorial Day recess.

“If we can get it, then we should get it done. I’m always somebody who believes, especially around here, you want to strike while the iron’s hot. I think if we’re ready to go, the committees have acted and we’re in a good place with the parliamentarian and we’ve got decent attendance here, then I think we want to try and wrap this up,” he said.

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