President Donald Trump’s selective endorsements continue to shape Republican primaries ahead of the 2026 midterms, with traders closely tracking signals of loyalty to his agenda and support for redistricting efforts that could expand House majorities. Recent developments include a series of May 2026 announcements backing candidates in competitive House and Senate races across Texas, Indiana, and other states, often timed with primary deadlines and aimed at sidelining perceived moderates. In the closely watched Texas Senate runoff between Attorney General Ken Paxton and Senator John Cornyn, Trump has delayed a choice despite earlier promises, citing positive views of both while facing pressure from early voting that begins May 18 and activist campaigns highlighting Senate procedural delays. Historical patterns show Trump’s backing frequently boosts primary margins for aligned candidates, though outcomes remain sensitive to last-minute campaign dynamics and party unity pressures before November.