President Donald Trump’s endorsement of embattled Texas Attorney General Ken Paxton was meant to send a message to Republicans everywhere, delivered in the language of Texas politics: Don’t mess with Trump.
The president’s 11th-hour backing of Paxton — a man previously impeached by the Republican-controlled Texas House and facing adultery allegations amid an ongoing divorce — over four-term incumbent Sen. John Cornyn was a sharp signal to Senate Republicans that lukewarm loyalty is no loyalty at all. The two face off Tuesday in a runoff that will test, in real time, just how far the president’s political grip on the GOP extends.
The Republican establishment in Washington has consolidated around Cornyn, who has the support of Senate Majority Leader John Thune, R-S.D., and Sen. Tim Scott, R-S.C., who chairs the National Republican Senatorial Committee. At least $76 million in campaign contributions and outside spending have flowed into the race over the course of the entire primary, with Cornyn commanding a lopsided advantage, according to the latest available campaign finance disclosures.
Even some in Trump’s closest orbit are backing Cornyn. Chris LaCivita — Trump’s 2024 co-campaign manager and longtime political adviser — has been advising a pro-Cornyn super PAC and has been vocally critical of Paxton, promising an aggressive race after the earlier March contest between the two.
But Trump had no interest in following suit. His endorsement of Paxton, people familiar with his thinking say, was aimed squarely at Senate Republicans who have not bent to his demands quickly enough.
Trump backing Paxton was an intentional “f*** you” to a stalled Republican Senate, said a White House official granted anonymity to speak candidly about the president’s thinking. “[Senate Republicans] didn’t do anything with the filibuster, they’re doing nothing with the SAVE Act, they are a problem every step of the way and I think he just finally had enough,” the official said.
Trump has the wind in his sails. His effort to build a GOP free from any internal dissent has steamrolled through the last several weeks of Republican primaries. On May 5, he ousted five state senators in Indiana who opposed his push to gerrymander the state ahead of the November elections. On May 16, he succeeded in defeating two-term incumbent Sen. Bill Cassidy, R-La., who voted to convict him in his second impeachment trial. On May 19, he was successful in knocking out seven-term incumbent Rep. Thomas Massie, R-Ky., a frequent critic of Trump’s war with Iran and his handling of the Epstein files.
Now, it’s Cornyn — a man whose campaign website touts the fact he’s voted with Trump 99.2% of the time — who doesn’t pass the loyalty test.
“He was not supportive of me when times were tough,” Trump said of Cornyn on Truth Social in his last minute endorsement of Paxton. “John was very late in backing me in what turned out to be a Historic Run for the Republican Nomination, and then, the Presidency.”
In any traditional sense, Cornyn entered this cycle with every advantage an incumbent could want.
Well-liked and reliably conservative, if pragmatic, Cornyn had long avoided the scorched-earth style of his fellow Texas Sen. Ted Cruz, instead cultivating a reputation as an elder statesman of the Republican Party. He dominated the money race before Trump picked a side, and benefited from the open support of the Senate GOP’s campaign arm — support that has left a paper trail of withering attacks on Paxton that Democrats are already poised to weaponize if the attorney general becomes the party’s nominee this fall. (“Crooked Ken Paxton’s incompetence and litany of baggage threatens President Trump’s Senate Majority” reads one 2025 news release from the NRSC.)
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But the Trump era has scrambled traditional political math. Loyalty to the president has come to matter more to Republican base voters than conventional conservative credentials or institutional standing. In less than two years, Cornyn went from a failed bid for Senate GOP leader to falling out of the president’s favor — his lengthy career in public service potentially ending in defeat to a candidate he has called corrupt.
The outside spending picture tells the story clearly. Since the two advanced to a runoff after the March 3 primary, close to $19 million in independent expenditures has poured into the race. Federal records show more than $13 million of that was spent opposing Paxton.
The donor lists lay bare the GOP establishment’s preference for Cornyn. Texans for a Conservative Majority, the main pro-Cornyn super PAC, has raised at least $36 million since 2025, drawing support from big-name GOP donors including Stephen Schwarzman, Kelcy Warren and the Ricketts family. Lone Star Liberty PAC, the primary pro-Paxton vehicle, has raised at least $8.2 million, with its top donors largely coming from within Texas, according to disclosure records.
But that financial advantage may prove no match for a Trump endorsement. And while Senate Republicans have generally shown their survival instincts in not challenging the president, his move against Cornyn appeared to make them especially uncomfortable. Leaving a meeting a day after Trump endorsed Paxton, some of his most loyal senate allies were circumspect, cautious or even downright mum.
“I’ve got other things on my mind right now other than the Texas race,” said Sen. Jerry Moran, R-Kan.
“Ask the president,” said Sen. Ron Johnson, R-Wisc., when questioned by MS NOW about the endorsement and what it says about Trump’s relationship with the base compared to that of elected officials.
The episode reflects one of the defining dynamics of Trump’s second term: his bond with the Republican base is central to his political power, and that base has consistently favored partisan fighters like Paxton over institutionalists like Cornyn — legal troubles notwithstanding.
“Cornyn crossed over a lot because if you look at his record, he had a liberal record, voting record, and we are the way we vote,” said Rep. Ralph Norman, a conservative Republican who is running for governor of South Carolina. “You look at your votes, you can tell what somebody’s core beliefs are. And the president figured that his core beliefs weren’t quite in line the way Paxton’s would be.”
Jake Traylor is a White House correspondent for MS NOW.
Hunter Woodall covers politics for MS NOW. He’s reported on politics and presidential campaigns for The Associated Press and CBS News and reported on Congress for The Minnesota Star Tribune.
Soorin Kim is a White House producer with MS NOW.