Ever since Richard Nixon walloped George McGovern in the presidential election of 1972, political pundits have treated as a truism the proposition that liberals are out of step with the rest of the nation, and therefore all but unelectable outside the precincts of the Northeast -- give or take a college town here or a ski resort there. During the course of every presidential election for the past forty years now, Republicans have sought to wield the word liberal as if it were a six-gauge shotgun.