Rep. Dan Crenshaw's defeat in Tuesday's Republican primary in Texas is more than the fall of a prominent conservative lawmaker — it reflects deeper structural changes reshaping the Republican Party in the nation's largest red state. Texas state Rep. Steve Toth unseated the four-term congressman in the GOP primary for Texas' 2nd Congressional District, marking the first time a sitting member of Congress has lost renomination in the 2026 election cycle. Mr. Toth ran an aggressive campaign from the right, arguing that Mr. Crenshaw was insufficiently aligned with the party's conservative grassroots and the political movement surrounding former President Trump. The upset highlights several forces transforming Republican politics in Texas, including growing ideological pressure from the right, the increasing importance of Mr. Trump's influence in primaries and political disruptions caused by mid-decade redistricting.