- Polymarket priced Texas Attorney General Ken Paxton at 95.5% to win Tuesday's Republican Senate runoff against incumbent Sen. John Cornyn, with Kalshi at 93.1%, after President Trump endorsed Paxton on May 19.
- Before the Trump endorsement, Kalshi had Paxton at 82% and Cornyn at 17%; the endorsement closed the door on what had still been a competitive runoff in public polling.
- A University of Houston poll from early May had Paxton ahead by 3 points, within the margin of error, suggesting markets are pricing the endorsement effect more aggressively than the polling.
- The general election just got tighter: Kalshi's Texas Senate market shifted from R+57% to roughly 50-50 after Trump's endorsement, reflecting Paxton's legal baggage and the state's appetite for a competitive November.
- Three other statewide runoffs are on the May 26 ballot: Mayes Middleton vs. Chip Roy for attorney general, Jim Wright vs. Bo French for railroad commissioner, plus the Democratic lieutenant governor primary and two competitive House district runoffs.
AUSTIN, Texas — Texas Republicans head to the polls Tuesday to settle a U.S. Senate primary that has stretched almost three months past the March 3 first round and ends with one of the most decisive prediction-market verdicts of the 2026 cycle. State Attorney General Ken Paxton is priced at 95.5% on Polymarket and 93.1% on Kalshi to defeat four-term incumbent Sen. John Cornyn, ending a contest that ran competitive in public polling right up until President Trump's May 19 endorsement of Paxton reshaped the race overnight.
The runoff also serves as the cycle's clearest test of how much Trump's endorsement is still worth in a contested Republican primary. Markets priced it at almost everything. Whether Tuesday's results validate that pricing is the story Texas Republicans will be reading the morning after.
The Senate Runoff In Texas
The Republican Senate runoff is the marquee race on Tuesday's ballot and the one driving virtually all the prediction-market volume in Texas. Polymarket's main market for the Republican nominee shows Paxton at 95.5% with Cornyn at 4.5%, levels traders consider close to settled. Kalshi's parallel market sits at 93.1% to 6.6%, with the gap between the two platforms inside the normal range for non-identical resolution criteria.
Both platforms repriced sharply between May 18 and May 20, when Trump moved from a non-endorsement stance to a formal endorsement of Paxton. New York Times reporting confirmed Trump had initially considered backing Cornyn after the March 3 result before ultimately going with Paxton on the recommendation of his political team.
The endorsement matters in Texas Republican primary electorates more than in many states. A University of Houston survey from early May found 77% of likely Republican runoff voters held a favorable opinion of Trump, with Vice President JD Vance at 81% and Sen. Ted Cruz at 76%. In an electorate that maps that closely to a single endorsement, the move from neutral to Paxton was always going to be heavy.
How We Got to a Runoff In Texas
The March 3 primary was an eight-way Republican Senate race that produced the closest top-line result of any major state primary this cycle. Cornyn finished first with 42.0%, Paxton second with 40.5%, and Rep. Wesley Hunt third at roughly 17%. Texas requires a candidate to clear 50% to win a primary outright, so the top two finishers headed to the May 26 runoff.
Hunt, the Houston-area congressman who had been the third major name in the race, did not advance and has not formally endorsed either runoff candidate, though his post-primary statements have leaned toward Paxton. Markets read his coalition as more likely to break for Paxton in the runoff than for Cornyn, an assumption the early polling supported.
The runoff was essentially decided by which candidate could consolidate the rest of the Republican coalition. Cornyn carried suburban and traditional-Republican primary voters in March. Paxton carried rural counties and the populist-right base. The Trump endorsement on May 19 settled the consolidation question on Paxton's side.
Ken Paxton
Paxton, 63, has served as Texas attorney general since 2015 and is one of the most controversial figures in Texas Republican politics. The Texas House impeached him in 2023 on 20 articles related to bribery and abuse of office, before the Texas Senate acquitted him on all counts the same year. He has been under federal investigation for securities fraud since 2015, a case that the Justice Department dropped in 2024.
His attorney general's office became one of the most aggressive conservative legal operations in the country during his tenure, suing federal Democratic administrations more than 30 times under the Biden presidency and intervening in election-related litigation across multiple states. That record made Paxton a hero to the populist wing of the Republican Party and a target for the institutional wing.
His Senate campaign was built around a single line: that Cornyn was a McConnell loyalist who would not fight for Trump's agenda. The endorsement on May 19 effectively confirmed that framing.
John Cornyn
Cornyn, 73, has held this Senate seat since 2002 and is the second-most senior Republican in the Senate after Mitch McConnell's 2025 retirement. He served as Senate Republican whip from 2013 to 2019 and ran for Republican leader after McConnell's exit before withdrawing in favor of Sen. John Thune. Cornyn is widely seen by the Republican institutional class as the safer bet to hold the Texas seat in a competitive November.
His campaign emphasized his judicial confirmations record, his work on the 2022 bipartisan gun safety legislation, and warnings about Paxton's legal vulnerabilities in a general election against Democrat James Talarico. Cornyn raised significantly more money than Paxton through the runoff period, including a reported $100 million pledge from outside groups, though Paxton's response framing that as evidence of establishment desperation appears to have landed with the primary electorate.
A Cornyn loss Tuesday ends a 22-year Senate career and one of the longer institutional runs in modern Republican politics. He has not indicated what he plans to do next.
The General Election In Texas Just Got Tighter
Texas Democrats already settled their Senate nomination on March 3. State Rep. James Talarico of Austin defeated Rep. Jasmine Crockett with 51% of the vote, becoming the Democratic nominee and clearing the field for the November general election. Talarico, a former San Antonio public school teacher, has spent the spring fundraising while Republicans fought their runoff.
The Talarico-Paxton matchup is what's reshaping the broader Senate map in real time. Kalshi's Texas Senate general election market moved from showing Republicans at 57% to roughly 50-50 after Trump's endorsement of Paxton, a 7-point repricing reflecting Paxton's legal baggage and the difficulty of running a controversial nominee in a state Trump won by 14 points in 2024 but where Democrats have made gains in suburban counties.
The Texas Tribune cited Hobby School polling that gave Cornyn a 1-point edge over Talarico in a hypothetical general but had the race much closer with Paxton as the nominee. Polymarket's main Texas Senate winner market has Republicans at roughly 65%, well below the 80%+ it would normally price for an open Senate seat in a deep-red state.
The implication for Senate control: Texas has gone from a near-certain Republican hold to a competitive race that Democrats can plausibly target with resources. If Paxton wins Tuesday, both parties will reallocate spending priorities accordingly.
The Other Runoffs on Tuesday's Ballot In Texas
Three other statewide Republican runoffs are on the May 26 ballot, plus a Democratic lieutenant governor primary and two competitive U.S. House district runoffs.
Attorney General (Republican)
State Sen. Mayes Middleton of Galveston and U.S. Rep. Chip Roy of Austin are competing to succeed Paxton as the GOP nominee. A University of Houston poll had Middleton ahead 48% to 39%, a 9-point margin outside the survey's margin of error. Middleton has spent more than $15 million of his own money on the race and earned Lt. Gov. Dan Patrick's endorsement; Roy entered as the frontrunner on name recognition but has run on a more libertarian-leaning conservative platform that has not consolidated the Trump-aligned base behind him.
Attorney General (Democratic)
Former Galveston Mayor Joe Jaworski faces state Sen. Nathan Johnson in the Democratic runoff. The winner faces the eventual Republican nominee in a general election that has historically been one of the harder lifts for Texas Democrats.
Railroad Commissioner (Republican)
Incumbent Commissioner Jim Wright faces challenger Bo French for the Republican nomination to the Texas Railroad Commission, the three-member body that regulates the state's oil and gas industry despite its name. The University of Houston poll had Wright leading French 35% to 28%, with 37% of likely voters undecided — the most unsettled of the three statewide runoffs.
Lieutenant Governor (Democratic)
State Rep. Vikki Goodwin of Austin and labor organizer Marcos Vélez of the Houston area face off in the Democratic primary for the right to challenge incumbent Republican Lt. Gov. Dan Patrick in November. Patrick, who has held the office since 2015 and easily won his March primary, is heavily favored in any general election matchup.
U.S. House: TX-30 and TX-33
Two Texas congressional districts have Republican runoffs. TX-30 (Dallas): Everett Jackson vs. Sholdon Daniels. TX-33 (Dallas-Fort Worth): Patrick Gillespie vs. John Sims. Both districts lean Democratic in the general election, but the GOP nominees will be on the ballot in November.
The Bottom Line
Texas Republicans go to the polls Tuesday with one of the most lopsided market expectations of the cycle pointing to a Paxton win. If markets are right, Cornyn's 22-year Senate tenure ends Tuesday night and the Texas Senate race becomes a genuine November contest rather than a foregone Republican hold.
If markets are wrong — if Cornyn outperforms his polling, if turnout patterns reward the candidate with more institutional backing, if Trump's endorsement turns out to matter less than the markets assumed — the runoff would produce one of the bigger prediction-market upsets in recent memory. The University of Houston poll showing Paxton up just 3 points within the margin of error suggests the gap between markets and polling has rarely been wider this cycle.
For readers tracking Texas election odds, the runoff resolution will reset the Senate map and the broader balance-of-power math heading into the summer. Both parties' strategists are watching Tuesday closely for what it tells them about Trump's continued grip on Republican primaries, the durability of incumbent Senate Republicans against populist challengers, and how aggressively to contest a state that may have just gotten interesting again. The full 2026 election odds picture updates as soon as the count comes in.
Polls close at 7 p.m. Central time Tuesday across most of Texas.
