President Trump threw his support behind Ken Paxton in the final week of Texas's GOP Senate runoff, delivering a major blow to incumbent John Cornyn. The endorsement came after Paxton leveraged his long-standing loyalty to Trump, including backing efforts to challenge 2020 election results, while Cornyn faced criticism for not being supportive during Trump's difficult times.

Trump's decision defied Republican Senate leadership, who viewed Cornyn as the stronger general election candidate. Party leaders had urged Trump to back Cornyn to avoid an expensive and divisive runoff, warning that electing Paxton could cost $100 million due to his scandals, including surviving indictment and impeachment proceedings.

The race has already proven costly, with over $70 million spent in the first primary round alone, breaking records for Senate incumbent spending. Super PACs have dumped another $15 million into the runoff campaign. Democrats have nominated state legislator James Talarico, though Trump has dismissed his viability.

Paxton's strategic maneuvering, including conditioning his potential withdrawal on Trump's voter ID legislation priorities, ultimately secured the endorsement. This sets up a contentious runoff that will test whether Trump's base support can overcome establishment Republican concerns about Paxton's electability in November.