Incumbent Republican Sen. John Cornyn, first elected in 2002, is seeking a fifth term in 2026. Cornyn faces major primary challenges from Attorney General Ken Paxton and Congressman Wesley Hunt in what is shaping up as a high-profile contest between the Texas GOP’s establishment and hardline conservative factions.  Paxton has attacked Cornyn for being insufficiently conservative, while Cornyn has criticized Paxton’s legal controversies and 2023 impeachment. Donald Trump has not endorsed a candidate but is seen as pivotal in deciding the race. Republicans have won every U.S. Senate election in Texas since 1990, and no incumbent senator has lost a primary since 1970.

In the 2024 presidential election, Donald Trump carried Texas by 14 points—his first double-digit win in the state and a sharp reversal from his single-digit margins in 2016 and 2020. Much of this surge came from massive Republican gains in South Texas, where heavily Hispanic border counties saw some of the largest rightward swings in the country, with several flipping Republican for the first time in over a century. The GOP holds every statewide office and commands large majorities in the state legislature and congressional delegation.