Whoever wins November’s presidential election is almost certain to face a Congress more ideologically divided than at any time in the past century. Though movement conservatives have accounted for much of the rise in hyperpartisanship, liberals have tried to match fire with fire in recent years. But highly partisan tactics, far from being politically neutral, actually strengthen conservatism and undermine liberalism. Instead of achieving their goals of advancing a progressive agenda, outfits like Media Matters and the Center for American Progress are self-defeating for liberals in the long run.