The decision by Texas Attorney General Ken Paxton to challenge Sen. John Cornyn (R-TX) in the state’s GOP primary is not only setting up a blockbuster contest between two Texas heavyweights, but is testing what it means to be a conservative Republican at a time when the party’s principles and values are rapidly shifting.

The contest pits Cornyn, a fixture in Texas politics for nearly four decades who served at the top levels of Senate leadership, against Paxton, the state’s scandal-plagued attorney general and a vocal supporter of President Donald Trump, in what is expected to be one of the highest-profile – and costly – intra-party fights this cycle. 

“It’s going to be really nasty and really expensive,” Matt Mackowiak, a Republican political consultant and the former chairman of the Travis County GOP, told Jewish Insider of the race. “Paxton is going to have to prosecute an intense, negative case that resonates with primary voters, but Cornyn is going to also prosecute a negative case with primary voters too.”

Cornyn has the support of many leading Republicans in Washington, including Senate Majority Leader John Thune (R-SD) and National Republican Senatorial Committee chairman Sen. Tim Scott (R-SC). The committee endorsed Cornyn’s reelection, and has lobbied Trump to back the incumbent. 

Cornyn is also one of the top fundraisers in the party: He spent over $33 million for his 2020 Senate reelection bid, and banked over $4.1 million in his campaign account at the end of last year. A hotly contested primary could require nearly $100 million, especially if Democrats plan to contest the seat amid the GOP divide.

One of the Republicans staying on the sidelines is Sen. Ted Cruz (R-TX), Cornyn’s more-outspoken Senate counterpart. Cruz offered an early endorsement of Cornyn well before his last reelection campaign in 2020, while Cornyn raised money for Cruz during the senator’s competitive race last year against Democrat Colin Allred. (Cruz, who has close ties with both Republicans, didn’t weigh in for Paxton during his 2022 reelection when he faced a spirited primary challenge from George P. Bush.)

“Both John and Ken are friends of mine, I have worked closely with both of them. I respect them both and I trust the voters of Texas to make that decision,” Cruz told reporters at the Capitol last week. 

In Paxton’s corner is Axiom Strategies, the Texas-based GOP consultancy founded by Jeff Roe, who is a close confidante of Cruz. While Roe is not personally involved with the Paxton campaign, his work as a top strategist for Ron DeSantis’ 2024 presidential super PAC could hurt Paxton’s ability to secure a Trump endorsement.

Paxton has also received two early endorsements from a pair of House Republicans, Reps. Lance Gooden (R-TX) and Troy Nehls (R-TX). 

Surrogates for both Cornyn and Paxton have been lobbying Trump and top White House officials to endorse their respective candidates, according to several sources familiar with the political efforts. Republican operatives advocating for a Cornyn endorsement have “expressed concerns to the White House that Paxton’s run would threaten Trump’s Republican Senate majority” and have highlighted his campaign’s ties to Axiom, one source said. 

“The specter of Trump’s involvement kind of hangs over this thing,” Mackowiak said, noting that whether he weighs in and whom he throws his weight behind would “fundamentally” impact the outcome.

Brendan Steinhauser, a Texas GOP operative and partner with Steinhauser Strategies, said that Trump’s decision to withhold his endorsement, which he described as “huge” and “potentially decisive in a race like this,” suggests there isn’t a clear favorite in the contest.

“[Trump] wants to back a winner,” Steinhauser told JI. “I just really think he’s going to stay out of it. There’s no reason for him to get involved in this. He has what he wants from both of these guys, and that is that they’re in lockstep politically. They’re loyal to the president. They’re going to be good foot soldiers for him. Why does he care who it is?”

Cornyn is expected to target Paxton over his many controversies in office, including accusations of bribery and other misuse of public resources, which led to his impeachment by the Texas House and a federal investigation. He was acquitted by the Texas Senate. Prior to serving in office, he was indicted on securities fraud charges, which were later dropped as part of a settlement agreement. Paxton has denied any wrongdoing on the corruption charges.

The Texas senator and his allies argue Paxton being the party’s nominee will put the state in play for Democrats, forcing national Republicans to allocate resources to an otherwise red state that could be used for races where Democrats are on defense. In last year’s Texas Senate race, Cruz spent over $103 million to fend off a serious challenge from Allred.

Paxton, meanwhile, is expected to focus his campaign messaging attacking Cornyn’s involvement in the successful 2022 bipartisan effort to enact gun control restrictions on individuals convicted of misdemeanor crimes of domestic violence, also known as the “boyfriend loophole,” and his support for arming Ukraine in its war with Russia, two issues that put the Texas senator at odds with the MAGA wing of the Republican Party. 

In a video announcing his campaign to unseat him, Paxton cited Cornyn’s comments in 2023 describing the charges against Trump related to his handling of classified documents as “very serious” and his prediction that same year that he did not believe Trump “could win the presidency” after being found liable for sexual abuse in a civil case. Cornyn’s relationship with Trump has improved since 2023, the result of the Texas senator doing considerable outreach to the president while he was running to be Senate Republican leader last year. 

A source familiar with the thinking of the leadership at Axiom cited Cornyn’s lack of “intensity” with the Republican base as a main reason for him being vulnerable to Paxton’s challenge. 

An internal poll by Fabrizio, Lee & Associates, commissioned by political allies of Paxton, showed Paxton leading Cornyn by over 20 points, findings Axiom sources point to as another reason for confidence that the incumbent senator is beatable. (The polling firm is also used by the Trump campaign.)

A public poll conducted in February 2025 by the University of Houston found Paxton with a slightly higher favorability rating (63%) than Cornyn (54%) among Texas Republican voters.

“People like to underestimate Cornyn, but they do so at their peril,” Mackowiak said. “He’s never lost an election. He’s 19-0, and his last three primary challenges he won by 30 to 40, and 70 points. He’s one of the greatest fundraisers in the history of the state of Texas, and he does it at the federal level, where you have $3,500 per person limits. Cornyn is going to run a highly sophisticated, well-funded, professional, aggressive effort.”

Steinhauser told JI that Paxton’s strong early polling in the race is as much a function of his strengths — an imposing profile in Texas state politics and appeal with the right-wing grassroots — more than any significant Cornyn vulnerabilities.

“[Paxton] certainly has a lot of support among very active, very conservative activists in the base. So I think that that is giving him a great opportunity at the beginning of the campaign. But if it was a different candidate, I don’t think we’d be talking about the race,” Steinhauser said

Both Republicans have touted their records in support of Israel and fighting against domestic antisemitism. 

Asked by JI in the Capitol this week what makes him a stronger candidate than Paxton when it comes to addressing the concerns of Jewish voters, Cornyn replied: “He’s a con man and I’ve got a demonstrated record of support. I think I’m probably at 100%. I keep asking AIPAC, ‘Can I do any better than that?’ And they’ve said, ‘No, that’s about as good as you can do.’”

Cornyn also argued that Republicans should “absolutely” be concerned that they could lose a Senate seat to Democrats if they were to nominate Paxton over him. “It would also be about a half-a-billion dollar race in money that would be more effectively spent in Michigan, in Georgia and in New Hampshire. So I think it’s a bad idea for him to run,” Cornyn said.

Jewish Insider’s senior congressional correspondent Marc Rod contributed to this report.