Cornyn and Paxton bury each other in negative ads as Senate GOP runoff enters final stretch

The incumbent senator and his allies have massively outspent the pro-Paxton side, though polling points to a tight finish in the May 26 election.

From the jump, the battle for the Republican U.S. Senate nomination has featured a massive cash imbalance, with incumbent U.S. Sen. John Cornyn and his allies in Senate GOP leadership unleashing millions in ads to pull him to a first-place finish in the March primary over Attorney General Ken Paxton.

That financial disparity has persisted in the runoff after neither Cornyn nor Paxton broke 50% of the vote in round one. Through Wednesday, pro-Cornyn forces had outspent the Paxton side more than four to one, according to media tracking firm AdImpact, allowing the incumbent senator’s allies to dominate the airwaves with ads attacking Paxton, a warrior of the far right, as incompetent, corrupt and adulterous.

Lackluster fundraising on Paxton’s side, meanwhile, has handicapped his ability to counter that messaging on TV, though he has ramped up his airtime in the week ahead of early voting, which begins Monday. Paxton’s spots in the runoff have tagged Cornyn as a generational relic, weak on red-meat issues and an ally to Democrats.

The spending gap, while still large, has narrowed since the first round, when pro-Cornyn groups — including Senate Republican leadership, which has been quieter on the airwaves in the runoff — spent $69 million, roughly 17 times as much as Paxton and his allies. Some of that paid for attack ads against U.S. Rep. Wesley Hunt of Houston, who placed a distant third in the March 3 primary after coming under fire from both sides.

“We were never going to be at dollar-for-dollar parity against the Washington, D.C. establishment and someone like John Cornyn, who’s got so many industries and corporations in his back pocket,” said Gregg Keller, a spokesperson for the pro-Paxton Lone Star Liberty PAC. “But the fact that we’ve been able to close the gap by such a huge margin — I think you’re going to see the results of that on election night.”

Even with the lopsided spending, Paxton has shown no signs of receding, according to a mix of limited public surveys and ample internal polling from both sides, which, taken together, point to a close finish. Pollsters have also captured a mostly calcified electorate, with one recent survey finding that just 7% of voters were undecided and more than 90% planned to stick with their pick from round one.

Ad spending does not go as far in runoff elections, which tend to draw the most motivated and engaged voters, said John Thomas, a Dallas-based Republican strategist who is not involved in the race.

Voters in the overtime round “probably have strong opinions to care that much to go turn out, meaning paid advertising has less of an effect on them,” Thomas said, adding that it’s particularly hard to move the needle when both candidates are as well known as Cornyn and Paxton.

The messaging has taken an almost entirely negative turn, an especially pronounced shift for Cornyn’s side after his allied groups focused more on promoting his MAGA bona fides ahead of March 3. The pivot, Thomas said, indicates that “the campaigns have determined they can’t move their own numbers, but perhaps they can disqualify the other.”

“Senator Cornyn has said that character is on the ballot in this runoff and we are educating Texas GOP voters about Ken Paxton’s mismanagement of his office, his personal enrichment, his indefensible behavior and his disqualifying judgment in child sex abuse cases,” Cornyn campaign senior adviser Matt Mackowiak said in a statement. “Ken Paxton has no one to blame but himself.”

The specter of November

The continued drain on GOP coffers is exactly what some Republicans saw hope of avoiding just after the March 3 election, when President Donald Trump teased an endorsement that early reports said would go to Cornyn. Trump appeared to be motivated by that very concern, saying he’d expect the candidate who he didn’t endorse to drop out for “the good of the Party,” adding, “We must win in November!!!”

But instead of dealing what could have been a mortal wound to either candidate’s campaign, Trump has stayed on the sidelines. He told reporters last week he would make a decision about an endorsement “maybe relatively soon,” adding, “I like them both.”

That has left the two GOP heavyweights to duke it out on their own in a brutal contest that has delighted Texas Democrats, who are hoping to win statewide for the first time since 1994 by capitalizing on Republican infighting and the favorable political climate generated by Trump’s slumping approval rating.

Paxton’s weaker fundraising is another factor adding to Democrats’ tentative optimism as they head into the fall with a fundraising juggernaut in James Talarico, the Austin state lawmaker who locked up the Democratic U.S. Senate nomination in March.

After seeing his fundraising taper off in each successive quarter of 2025, Paxton brought in his largest haul yet over the first three months of the year — $2.2 million across his main campaign account and a joint fundraising committee. Meanwhile, Cornyn raised about $9 million between the accounts affiliated with his campaign, and Talarico took in a record-breaking $27 million.

Cornyn and his allies have argued throughout the primary that Paxton, if chosen to lead the ticket, would alienate swing voters and sink down-ballot Republicans in November. The main pro-Cornyn super PAC, Texans for a Conservative Majority, made that case even more explicitly this month when it rolled out data showing a down-ballot wipeout with Paxton as the nominee.

“The strategy speaks for itself: Ken Paxton is a bad guy, an attorney general who broke the law, who has serious personal issues and flaws that I think most Texans find repulsive,” said Aaron Whitehead, executive director of Texans for a Conservative Majority. “The issues that we’re talking about — Republican runoff voters by and large agree with.”

Scorched earth down the homestretch

Paxton’s side, meanwhile, has released internal polling that puts the attorney general up 11 percentage points over Cornyn. A survey fielded a few weeks ago by the University of Houston found Paxton ahead by three points.

Early in the runoff, Lone Star Liberty, the pro-Paxton super PAC, spent almost $10,000 on airtime in West Palm Beach, where Trump’s Mar-a-Lago estate is located, for an ad aimed at an audience of one.

“John Cornyn betrayed President Trump, and he doesn’t deserve our trust,” the ad says after running through Cornyn’s past praise for prosecutors and lawyers who investigated Trump.

Other pro-Paxton spots have hit Cornyn on his past criticism of Trump’s southern border wall; the senator’s work on a bipartisan gun safety bill after the Uvalde school massacre; and his lengthy tenure in public office, seizing on a broader anti-incumbent mood prevalent among voters of all political stripes.

“After 42 years in office, can you name a single thing career politician John Cornyn has done for you?” one ad run by the Paxton campaign asks while depicting Cornyn next to former House Speaker Nancy Pelosi and other Democratic leaders. “Not one, unless you’re a Democrat. Trump’s right: Cornyn is ‘weak, ineffective and very bad for the Republican Party.’”

Paxton’s most recent ad, first aired Wednesday, dubs the senior senator “Caliphate Cornyn,” casting him as weak on combating immigration and Sharia law — a recent fixation of the right, which has embraced anti-Muslim and anti-Indian rhetoric under the banner of fighting “radical Islam” and curtailing H-1B visas.

Cornyn, meanwhile, has offered the sole positive ad of the runoff, touting his efforts to strengthen border security and his endorsements from law enforcement groups, including the National Border Patrol Council.

Other spots, pushed by allied groups, portray Paxton as an adulterer “distracted” on the job as attorney general. One ad, run by Texans for a Conservative Majority, accuses Paxton of funneling public grant dollars to left-wing boogeymen, including “trans activists who fund gender transition surgery recovery” and “groups that fight [Immigration and Customs Enforcement], teaching illegals how to avoid being deported.”

More recently, pro-Cornyn ads have homed in on how Paxton’s office has handled specific child sex abuse cases.

“Arrested for trafficking young girls — sold, abused — facing life in prison, but Ken Paxton cut him a deal: no prison, no sex offender registry, no justice for the victims,” says the narrator in an ad that Texans for a Conservative Majority spent $4.5 million to run all over the state for the past two weeks.

Cornyn Lonestar Victory Fund, one of the senator’s joint fundraising committees, booked $2.1 million in airtime for another ad featuring mugshots of alleged child sex offenders as a narrator warns that, “while predators hunted children, Paxton hunted for burner phones to hide his affairs.”

“Texas law enforcement knows Ken Paxton,” the ad says. “That’s why Texas law enforcement has endorsed John Cornyn.”

Source: Kayla Guo, The Texas Tribune

Photo Credit: From left: U.S. Sen. John Cornyn, President Donald Trump and Texas Attorney General Ken Paxton. Cornyn and Paxton are locked in a tight runoff for the Republican nomination for Senate; Trump has so far endorsed neither. Bob Daemmrich for The Texas Tribune | Sipa USA via REUTERS | Pheobe Terry for The Texas Tribune

The Texas Tribune is a nonprofit, nonpartisan media organization that informs Texans — and engages with them — about public policy, politics, government and statewide issues.

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