Trump's anticipated endorsement in the Texas Republican Senate primary runoff on May 26 between incumbent John Cornyn and challenger Ken Paxton drives much of the market focus, following his early March tease of a decision "soon" amid Paxton's polling momentum and pressure from conservative activists opposing Cornyn. No announcement has come in the past 30 days despite meetings and leaks suggesting initial leans toward Cornyn before backlash. Recent endorsements for Steve Hilton in the California governor race on April 6 and Lindsey Graham's South Carolina Senate reelection around April 11 highlight Trump's active role in 2026 primaries, where his backing has succeeded in over 90% of contests. The Texas deadline looms as the key catalyst.