Postmodernism is a philosophy that refutes the notion of objective reality. It refutes the Enlightenment notion that Man advances his situation mainly though reason. Enlightenment philosophies are the basis of modern Western democracies in general, and of the United States in particular. Enlightenment thinking stands in the way of establishing a collectivist Utopia, and so must be supplanted in the body-politic by the post-modern viewpoint. Postmodernism can be said then, to be the philosophic means to that collectivist end.
Those who strive for a godless Utopia have been met by an ever-increasing opposition and the societal momentum of their movement has stalled. It's stalled because it has caused misery, not happiness and its false promises are, if not being rejected, are at least being met by skepticism.
So are the leftist Democrats in power really just inept or is all the destruction being caused to our society and economy just a price to be paid to achieve the collective Utopia they seek?
St. Thomas Moore had his Utopia, Marx and Engels had their Communist Manifesto. Though the latter is better known for the destructive nature of its implementation in this and the last century, it has a commonality with the other books mentioned: the necessity of authoritarianism. It is this need for an authoritarian form of government and a ruling class, either explicit as in the Republic or implicit as with Marx and Engels that binds most, if not all Utopian systems with each other.