Senator John Cornyn and state Attorney General Ken Paxton head to a Tuesday runoff after neither captured a majority in the March primary. Cornyn won about 42 percent of the vote, just ahead of Paxton's more than 40 percent. The race has been ugly and expensive, with President Trump's endorsement of Paxton delivering the biggest boost heading into the final stretch.

Paxton launched his challenge in April 2025 with a campaign site featuring a photo of him and Trump. Weeks later his wife, state Senator Angela Paxton, filed for divorce citing adultery. Representative Wesley Hunt's late entry in October created a three-way race that triggered a runoff.

A Paxton victory risks weakening the GOP's general election chances, a concern among national Republicans. Trump's endorsement remains the most powerful GOP seal of approval despite the president's second-term approval rating hitting a low. Cornyn's cash advantage secured a first-place finish but no outright win, making Tuesday's vote a direct test of Trump's political pull.