U.S. Sen. John Cornyn’s year-long effort to demonstrate his loyalty to President Donald Trump could not save his political career. On Tuesday, the four-term Texas Republican lost his Senate primary runoff to state Attorney General Ken Paxton by a double-digit margin, becoming the latest GOP officeholder to fall to a primary challenger after losing the president’s backing.
The Associated Press reported that Cornyn had undertaken a series of moves meant to signal his alignment with Trump. He posted a photograph of himself reading Trump’s book “The Art of the Deal,” proposed legislation to rename a stretch of interstate highway in Trump’s honor, and—perhaps most consequentially—abandoned his long-held support for the Senate filibuster in a failed push for voting restrictions that the president has championed. Cornyn’s campaign also emphasized his votes to confirm Trump’s nominees and his support for the administration’s agenda.
None of it was enough. Trump endorsed Paxton last week, describing him in a statement as “a true MAGA Warrior.” Paxton’s campaign featured the endorsement in advertising and on the trail, and the attorney general’s double-digit victory on Tuesday underscored the weight Trump’s word now carries with Texas Republicans.
Cornyn entered the Senate in 2002 and rose to become a member of the Republican leadership. His tenure was marked by a reputation as an institutionalist—someone who valued the chamber’s rules and traditions, including the 60-vote threshold that his filibuster reversal targeted. By the time of the runoff, however, his efforts to accommodate Trump’s priorities had not convinced the president or the primary electorate.
The AP also noted that Cornyn’s loss extends a pattern that has reshaped the Republican Party over the past decade. Former Sen. Jeff Flake of Arizona and other incumbents who criticized or lost favor with Trump were similarly ousted by primary challengers who ran to their right. Trump’s willingness to back challengers against sitting members of his own party has made party loyalty to him a defining litmus test in GOP primaries across the country.
Cornyn will remain in office until his term expires in early 2027. Paxton will face Democratic opposition in the November general election.