Last weekend, at a dusty race car track in that part of New Jersey where lacrosse fields slowly give way to farmland before the landscape seems to stop altogether, Sarah Palin rallied a couple of thousand partisans on behalf of Steve Lonegan, a longshot, Tea Party-fueled candidate for the U.S. Senate. “I just told Todd,” she said to the crowd a moment after they stopped chanting her name. “‘Ooh,’ I said. ‘I can die and go to heaven now: I just shook Mark Levin’s hand.’” Levin had been out earlier, warming them up. He cuts a figure that is the...