Republican and Democratic primary elections reveal starkly different party anxieties: Republicans face Trump's revenge campaign against disloyal members, while Democrats grapple with voter fury at establishment leaders. As Shane Goldmacher, Lisa Lerer, and Reid Epstein explain, these contests will shape which party controls Congress and signal how deep each party's internal divides run. Trump is systematically targeting Republican state legislators and congressmen who refused his demands, particularly in Indiana where he's funding primary challenges to eight state senators who blocked redistricting efforts.