Pedro Ramirez, a get-out-the-vote organizer in California’s Central Valley, has a grudge. And his anger is part of a potent force that could bounce as many as three Trump-aligned Republicans from the US House during next month’s midterm elections—if it can overcome the region’s deep political inertia. Ramirez’s beef started just over a decade ago, when he was a high school senior in Tulare County.