Reduced to its essentials, populism is America’s way of expressing class antagonism. It is a tradition of rhetorical protest that extends from Jefferson to Franklin Roosevelt to Bernie Sanders and on to the guy who just cooked your hamburger or filled your gas tank . It is powerful stuff. But protest isn’t the property of any particular party. Anyone can be the voice of those who work, and when one party renounces its claim the other can easily pick it up.