Slavoj Zizek doesn't directly address the limits of the U.S. two-party system in his latest book, Living in the End Times. But the Slovenian scholar does recognize a "deadlock" in American politics, and he argues that it results from contradictions inherent to classical liberalism, the tradition from which both modern "liberalism" and American entrepreneurial conservatism derive.
Today, the meaning of 'liberalism' moves between two opposed poles; economic liberalism (free market individualism, opposition to strong state regulation, etc.) and political liberalism (with an accent on equality, social solidarity, permissiveness, etc.) In the U.S., Republicans are more liberal in the first sense and Democrats in the second. The point, of course, is that while one cannot decide through closer analysis which is the 'true' liberalism, one also cannot resolve the deadlock by proposing a kind of 'higher' dialectical synthesis, or 'avoid the confusion' by making a clear distinction between the two senses of the term. The tension between the two meanings is inherent in the very content that 'liberalism' endeavors to designate, it is constitutive of the notion itself, so that this ambiguity, far from signaling a limitation of our knowledge, signals the innermost 'truth' of the notion of liberalism.
For Zizek, disagreements within the liberal tradition, positions that appear to be diametrically opposed to one another, reveal the contradictions within the core liberal ideology. In an aside, he identifies Ayn Rand as the exceptional unconflicted liberal of the 20th century because she "advocated both market liberalism and a full individualist egotism deprived of all traditional forms of morality concerning family values and sacrifice for the common good." More provocatively, he goes on to assert that lesser-evilism is inherent to liberalism.
An anti-ideological and anti-utopian stance is inscribed into the very core of the liberal vision: liberalism conceives itself as a 'politics of the lesser evil,' its ambition is to bring about the 'least worst society possible,' thus preventing a greater evil, since it considers any attempt to directly impose a positive good as the ultimate source of all evil. Churchill's quip about democracy being the worst of all political systems, with the exception of all the others, holds even better for liberalism. Such a view is sustained by a profound pessimism about human nature: man is a selfish and envious animal, and if one attempts to build a political system appealing to his goodness and altruism, the result will be the worst kind of terror.
Zizek's own alternative, as a Marxist and a kind of neo-Leninist, is to take the risk of "enforcing the Impossible onto reality" in the hope of at least "chang[ing] the coordinates of what appears as 'possible' and giv[ing] birth to something genuinely new." If that sounds like it might end in tyranny and terror, he argues that liberalism itself has an almost unconscious tyrannical tendency. He describes something others have noticed, the paradox that compels those most vocally opposed to state power to claim the maximum state power in order to keep others from abusing it.
However, the liberal critique of the 'tyranny of the Good' comes at a price: the more its program permeates society, the more it turns into its opposite. The claim to want nothing but the lesser evil, once asserted as the principle of the new global order, gradually replicates the very features of the enemy it claims to be fighting against. The global liberal order clearly presents itself as the best of all possible worlds; its modest rejection of utopia ends with the imposition of its own market-liberal utopia which will supposedly become reality when we subject ourselves fully to the mechanisms of the market and universal human rights. Behind this lurks the ultimate totalitarian nightmare, the vision of a New Man [or Nietzschean "last man"] who has left behind all the old ideological baggage.
Today's "postmodern" liberalism (or "liberal multiculturalism") is driven by historicism and the "hermeneutics of suspicion" to distrust all appeals to universal values. The postmodern liberal, Zizek suspects, believes that "the call to sacrifice our life for a higher cause is either a mask for manipulation by those who need war to sustain their power and wealth, or a pathological expression of masochism [or both]." This is the liberalism of "this atomized society, in which we have contact with others without entering into proper relations with them." If liberals of the "left" and "right" alike reject or recoil from positive (or "progressive") appeals to change their lives and their relations, or to adopt new values, and automatically distrust such appeals as self-interested power grabs, then liberal politics is inherently if not inevitably reactionary in nature, and lesser-evilism would be its natural expression.
Zizek quickly moves on to other subjects in his typical rambling, digressive fashion; this section on liberalism appears in the middle of a chapter that begins and ends with a consideration of the French ban on Muslim veils. He's also after bigger game than the American Bipolarchy, but for those of us for whom that's target number one, Living in the End Times may have more insights on our situation and the challenges it presents. If so, I'll let you know.