Former Texas Attorney General Ken Paxton defeated incumbent U.S. Senator John Cornyn in the Texas Republican Senate primary runoff on Tuesday, securing the GOP nomination for the seat Cornyn has held since 2002. Paxton, who received the endorsement of President Donald Trump, won by a substantial margin, ending the tenure of one of the Senate's most senior Republicans.

Cornyn, who had served as Senate Majority Whip and was considered a pillar of the Republican establishment, was unable to overcome the enthusiasm Paxton generated among the party's base. Trump's endorsement of Paxton proved a decisive factor, reinforcing a pattern of Trump-backed candidates dispatching establishment figures in Republican primaries during the 2026 midterm cycle.

Paxton, who survived an impeachment effort by the Texas state legislature in 2023, will now advance to the general election as the Republican nominee. Texas remains a reliably Republican state in statewide races, making Paxton a strong favorite in November. His win further consolidates the influence of the MAGA movement over the Republican Party's direction heading into the 2026 midterms.

The result drew wide coverage across the political spectrum, with analysts noting the significance of a sitting incumbent senator losing a primary runoff — a rare occurrence in American politics. Cornyn had been a key legislative figure in Washington, playing roles in major bipartisan negotiations over the years, including on immigration and gun legislation.

With Paxton's victory, the question turns to the general election and whether Democrats can mount a competitive challenge in Texas. The state has trended more competitive in recent cycles, though Republicans have continued to win statewide offices.