Texas Attorney General Ken Paxton crushed four-term incumbent Sen. John Cornyn in the Republican Senate primary runoff on Tuesday, turning a race that had been nearly deadlocked into a 27-point rout just one week after securing President Trump's endorsement. Paxton captured 63.8% of the vote to Cornyn's 36.2%, the New York Post reported, ending Cornyn's 23-year Senate career and delivering the clearest signal yet of Trump's dominance over the Republican primary electorate.
The margin was staggering by any measure. In the March 3 primary, Cornyn had actually led Paxton by 2.5 points. Neither man reached the 50% threshold required to avoid a runoff. Between March and the runoff, the race tightened to a dead heat, a Texas Southern University/YouGov poll released May 18 showed both candidates at 45%.
Then Trump weighed in. One week later, the incumbent senator was finished.
Trump announced his endorsement of Paxton on May 19, calling him "The Highly Respected Attorney General of Texas" and "someone who has always been extremely loyal." In his endorsement statement, Breitbart reported, Trump gave Paxton his "Complete and Total Endorsement" and labeled him "an America First Patriot," while criticizing Cornyn for not being supportive "during tough times."
Trump described Cornyn as "VERY disloyal," Fox News reported, and called Paxton "a true MAGA Warrior who has ALWAYS delivered for Texas, and will continue to do so in the United States Senate."
Paxton acknowledged the weight of that backing in his victory remarks:
"When everyone in Washington told him to abandon me and abandon the people of Texas he didn't listen. Instead, he gave his complete and total endorsement."
He called Trump's endorsement "the most powerful force in politics", a description the numbers bore out. A swing of roughly 30 points in the span of a single week does not happen by accident. It happens when the most influential figure in Republican politics picks a side.
The Texas Senate primaries were the most expensive in American history. Ad tracking firm Adimpact reported that total advertising spending exceeded $110 million. More than $64 million of that went to ads boosting Cornyn.
None of it mattered. The 74-year-old senator, who had served in Washington since 2002 and held leadership posts including Senate Majority Whip, could not overcome a one-week-old endorsement from a president whose approval among Republican primary voters remains unmatched. Senate Majority Leader John Thune and the National Republican Senatorial Committee had reportedly urged Trump to endorse Cornyn as the "safe choice." Trump chose otherwise.
The pattern is now well established. Trump-backed challengers have toppled longtime Republican incumbents in recent cycles, including Sen. Bill Cassidy in Louisiana and Rep. Thomas Massie in Kentucky. Paxton's victory over Cornyn is the biggest scalp yet, a senior senator with deep fundraising networks and establishment support, swept aside by a one-week endorsement.
Cornyn, to his credit, conceded gracefully. He told supporters he trusted the voters of Texas and respected their decision.
"I've spent most of my time in the Senate building the Republican Party in Texas... and I've always supported the Republican ticket, and I intend to do so again in this general election."
He added: "My hope is to keep my party in power for generations."
Paxton, 63, brings a combative conservative record to the general election. As attorney general, he has sued the Biden administration more than 100 times over what he described as "open borders policies, government overreach, attacks on the Second Amendment, and the far-left's radical agenda." That litigation portfolio gave him a strong claim on the MAGA base.
But his record also carries weight of a different kind. In 2015, Paxton was indicted on securities fraud charges. Those charges were later dismissed. In 2023, the Texas House impeached him over allegations that he obstructed justice in the securities fraud case, gave preferential treatment to a donor, made false statements against whistleblowers, and misappropriated public resources. He was suspended from his duties during the state Senate trial but survived the impeachment vote 16, 14.
That history gave Cornyn and his allies ammunition during the primary. It will give Democrats ammunition in the fall. Democratic nominee James Talarico, a 37-year-old state representative who defeated Rep. Jasmine Crockett in the March Democratic primary, wasted no time framing the race in those terms. The Washington Examiner reported Talarico called Paxton "the most corrupt politician in America."
Paxton fired back just as hard, calling Talarico "the most extreme radical the Democrats have ever nominated" and "a threat to everything we hold dear in this state and in this country."
The November 3 general election will carry national consequences. The New York Post noted the race "will go a long way to determining whether Republicans can maintain control of the upper chamber." No Democrat has won a Texas Senate seat since Lloyd Bentsen was elected to his fourth term in 1988, a 38-year drought that makes the Lone Star State one of the GOP's most reliable firewalls.
But the May 18 poll showing Paxton and Talarico tied at 45% apiece suggests the race could be competitive. Some Republican strategists have warned the contest could be costly and difficult for the party. Cornyn, for his part, had polled slightly better against Talarico than Paxton did, a fact that fueled the establishment argument for keeping the incumbent.
GOP leaders moved quickly to close ranks after the result. Newsmax reported that the result marked the latest in a series of Trump-backed challengers toppling longtime Republican officeholders. Texas Gov. Greg Abbott and state House Speaker Dustin Burrows immediately rallied behind Paxton. Sen. Bernie Moreno urged the party to unify, saying: "The voters have spoken, now Republicans must unite and win."
Not every Republican was so gracious. Sen. Thom Tillis went on CNN and called Paxton "a failure" who "doesn't deserve to be in the U.S. Senate." Rep. Don Bacon also publicly criticized Trump's endorsement, expressing concern about the president targeting "respected senators."
That kind of intra-party sniping is exactly what Democrats are counting on. Trump's influence over the Republican base has reshaped candidate decisions across the country, and the question now is whether the party can consolidate fast enough to hold a seat it has owned for nearly four decades.
The Paxton-Cornyn runoff was, at bottom, a test of two competing theories of Republican politics. Cornyn represented the institutional model: seniority, fundraising muscle, legislative deal-making, and the assumption that incumbency confers an advantage. He had $64 million in supportive advertising and the backing of the Senate leadership.
Paxton represented the insurgent model: a combative conservative record, an outsider posture, legal battles that endeared him to the base, and a willingness to fight the establishment on its own turf. He had Trump.
Trump won. It wasn't close.
The broader lesson is one that Republican incumbents across the map should absorb carefully. Seniority, committee assignments, and donor networks are assets, but they are not shields against a primary electorate that takes its cues from the president. The current election cycle has already seen dramatic shifts in candidate fields nationwide, and the Texas result will accelerate that dynamic.
For Cornyn, the defeat ends a long career in the Senate. He pledged to support the Republican ticket and keep the party in power. Whether his colleagues in Washington take that same approach, or continue airing grievances on cable news, will say a great deal about whether the GOP can hold this seat.
For Paxton, the real fight begins. A tied general-election poll, a well-funded Democratic opponent, and a political record that includes both 100-plus lawsuits against the Biden administration and a survived impeachment trial make this anything but a sleepy November contest. The volatility reshaping races in both parties suggests nothing in 2026 can be taken for granted.
Sixty-four million dollars in ads could not save John Cornyn. One endorsement from Donald Trump ended the argument in a week. Republican voters in Texas made their priorities clear, and Washington would be wise to listen.
