Nose-Holders for Nader?

One obvious conclusion to draw from this election debate is that the nuanced worldviews of Catholic moral and social teaching do not find an especially welcoming home in a two-party system. The Democratic and Republican parties are able to divide the spoils of our enormously diverse citizenry into overbroad and misleading categories, offering fixed agendas on a take-it-or-leave-it basis. Pro-life Democrats are forced to lend support to the "mainstream"-ing of abortion and start-up of the embryonic stem cell assembly line, and Common Good Republicans have to narrow their conceptions of "common" and "good" to justify embracing a corporate, devolutionary, and us-versus-them agenda. If the political landscape was populated by an array of parties, battling it out for hearts and minds, not in a zero-sum contest of blue state / red state polarization, but as part of a system where coalition building and intercommunity dialogue were an essential part of politics, would not that be fertile ground for the entry of policy positions that are not amenable to either/or classification?

So instead of holding our noses and voting for one or the other, or staying home entirely (which will be attributed in all likelihood to apathy, not principled objection), is there something to be said for casting a principled vote in favor of a multi-party system? Especially for those of us who are not in contested states, wouldn't a vote for Nader (or other third-party candidate) represent a step in the right direction, even if the particular candidate may not be a substantive improvement on Bush or Kerry?

Rob