"Politics makes for strange bedfellows," the old saying goes. Americans, however, often forget the obvious lesson underlying this adage: politics is about winning elections and governing once in office. Voters of all stripes seem put off by the rough-and-tumble horse-trading and deal-making of politics, viewing its practitioners as self-serving and without principle or conviction.

Because of these perspectives, the scholarly and popular narrative of American politics has come to focus on ideology over all else. But as Donald T. Critchlow demonstrates in his riveting new book, this...