Trump’s Paxton endorsement jolts Cornyn in Texas runoff

Texans vote Tuesday in a Republican Senate runoff between incumbent U.S. Sen. John Cornyn and state Attorney General Ken Paxton, closing a bitter, expensive primary in which President Donald Trump’s late endorsement has become the swing factor. Cornyn, whose c

On a Monday that comes right after Memorial Day, Texas Republicans are heading to the polls with a familiar kind of pressure: show up, pick a side, and decide whether the party stays aligned with President Donald Trump’s brand of loyalty.

Tuesday’s runoff will determine the Republican nominee for U.S. Senate, with Attorney General Ken Paxton challenging four-term Sen. John Cornyn. The contest arrives at the end of a long. bitter. and expensive primary in which Trump personally weighed in late—an endorsement that gives Paxton a new boost and puts Cornyn at risk of failing to win the party’s nomination. For Cornyn. it’s a deeply personal test: if he loses. it would make him the first Republican senator in Texas history to seek the party’s nod and lose.

Trump endorsed Paxton after early voting began. and his move landed like a jolt precisely because it came when many Republicans already had their ballots. In a social media post on May 18. Trump wrote. “Ken Paxton has gone through a lot. in many cases. very unfairly. but he is a Fighter. and knows how to win. ” adding. “Our Country needs Fighters. and also Loyalty to the Cause of Greatness.”.

Cornyn acknowledged the endorsement’s impact, but insisted he wouldn’t fold. Hours after Trump’s announcement, Cornyn said, “I know who gets to choose our senators, and it’s the people of Texas,” framing the moment as a choice Texans would still make for themselves.

The price tag of getting here has been staggering. Cornyn’s campaign and allied groups have spent roughly $90 million in advertising since last year. the vast majority of it attacking Paxton. The negative push has not been subtle. and it has been aimed at turning Paxton’s personal and legal controversies into political liabilities.

Paxton’s campaign began airing ads promoting Trump’s endorsement within 24 hours of Trump’s announcement. alongside a pro-Paxton super PAC. The ad buy is part of the reason analysts expect the endorsement to do more than shift headlines; it’s already feeding into the ground-level rhythm of persuasion.

The timeline itself is a sharp contrast with what Trump promised. During the primary, Trump had said he would endorse immediately after the result and asked the unchosen candidate to withdraw. But he didn’t act until after early voting began on May 18.

That delay matters because Texas politics—especially in runoffs—can be brutal about turnout. About 2 million of Texas’ 18.7 million voters participated in the GOP primary. Texas Republican strategist Tyler Norris. not affiliated with either campaign. warned that the election is being dragged down by hyper-negative messaging that can sap participation. He said. “The defining battle lines are based around hyper-negative messaging. which dampens turnout to begin with. ” and that the race may ultimately be decided by “who is going to show up… so who is going to show up is the hardest of the hard core.”.

Cornyn’s lead in March didn’t hold. He finished ahead of Paxton in the March primary but failed to win a majority in the three-way contest that also included U.S. Rep. Wesley Hunt, who finished a distant third. The runoff now turns that narrow failure into a straight contest.

The fight has been shaped by allegations and legal history that never stayed in the background. Paxton was acquitted in a 2023 impeachment trial after allegations of extramarital affairs surfaced. Last year, Paxton’s wife filed for divorce, citing “biblical grounds.”

The ad war leading into the runoff has also kept moving. Pro-Cornyn groups continued to attack Paxton over the attorney general office’s handling of a Waco sex abuse case. Pro-Paxton groups. for their part. seized on Cornyn’s relationship with Trump. arguing it put him at a disadvantage when it counted.

Trump’s own words fed that accusation. In endorsing Paxton. he said Cornyn “was not supportive of me when times were tough” and that “John was very late in backing me.” Trump has used similar language in other GOP primary battles where he has sought to punish incumbents he views as insufficiently loyal.

This month. he has successfully backed challengers to incumbents in Louisiana. Kentucky and Indiana. a sign of his enduring influence among primary voters. The approach has put party leadership on notice. In Texas, Senate GOP leaders backed Cornyn, saying he would be stronger in the general election.

Yet a growing number of GOP strategists have argued that a Paxton nomination could cost far more money in the fall—money that might otherwise be used defending Republican seats in more competitive states. Democrats would need a net of four seats to take the majority.

The contrast between the candidates is not only about personality; it’s also about how they have tracked Trump politically. Cornyn suggested in 2023 that Trump could not win the presidency again in 2024 and that his “time has passed him by.” He was also an early critic of Trump’s plan for a border wall between the U.S. and Mexico—a project he now supports.

Trump’s endorsement also carried an additional layer of political drama because it came after he publicly snubbed Cornyn’s kind of establishment alignment elsewhere. On May 16, Trump blasted Republican Louisiana Sen. Bill Cassidy as “a Disloyal Disaster” before Cassidy lost a GOP primary for the office he has held since 2015. Cassidy had voted to convict Trump after his 2021 impeachment trial over the Jan. 6, 2021, attack on the U.S. Capitol. Trump backed U.S. Rep. Julia Letlow, who advanced to a runoff with John Fleming, the state treasurer, while Cassidy finished well behind them.

Last week, Trump celebrated after Kentucky Rep. Thomas Massie—who has criticized the Trump administration’s handling of the Jeffrey Epstein files—lost his primary to Ed Gallrein. Trump called Massie “the worst congressman in the history of our country.”

For Cornyn, the stakes are not abstract. If he loses. it reshapes what it means to be a major Republican institution in Texas—because Cornyn has been a central figure in Senate GOP leadership for years. and he now faces the possibility of being overturned by a challenge tied to Trump’s immediate approval.

The winner of Tuesday’s runoff will advance to the general election in November against Democratic state Rep. James Talarico.

The same day will also decide several other nominations across Texas, giving the runoff a broader map-reading significance than a single race.

Democrats are choosing U.S. House nominees in districts in Dallas and Houston where the districts overwhelmingly support Democrats, as well as in a San Antonio-area seat where Democrats hope to flip.

In Texas’ 18th District, newly elected Rep. Christian Menefee and veteran Rep. Al Green are vying for the party nod. The Republican-led Texas Legislature redrew the district last year to help the GOP. That new map produced a contest between incumbents and marked the end of a chaotic series of elections in the Houston area. Menefee was elected in a special runoff in January to a seat held by the late Rep. Sylvester Turner, who died in March 2025. Menefee finished narrowly ahead of Green in the March 3 primary but did not win a majority to avoid the runoff.

In the Dallas-area 33rd District, former Rep. Colin Allred and U.S. Rep. Julie Johnson are competing for the Democratic nomination. Johnson was elected to the seat in 2024, the year Allred lost his U.S. Senate challenge to Republican Sen. Ted Cruz. Allred had been running for Senate again this cycle but dropped his bid and instead is looking to return to the House.

Near San Antonio. Democratic leaders are trying to prevent Maureen Galindo. who has expressed antisemitic views. from winning the party’s runoff with Johnny Garcia. While Texas lawmakers redrew the 35th District to help Republicans. Democrats view it as within reach and don’t want Galindo’s past comments to impede them.

The election results will close out a primary season that has been defined less by policy than by loyalty tests—especially the ones attached to Trump’s endorsements. For Cornyn. the challenge is clear: he must overcome not only an opponent’s record and controversies. but the late timing of a presidential push that arrived after early voting had already started on May 18.

Texas Senate runoff John Cornyn Ken Paxton Donald Trump endorsement May 18 early voting James Talarico GOP primary Bill Cassidy Julia Letlow Thomas Massie Tyler Norris