This weakness is a time bomb when the American political system is under severe stress.
Our country was started before parties existed, and no one imagined they would arise. Instead, our Founders thought elections would have a great many individual candidates running independently. Majorities would often be impossible and runoffs were impractical and in many cases unknown. Plurality election seemed a sensible solution. But parties soon arose and the Founders' system never worked as they thought it would. Nevertheless, because political parties were decentralized and government at the national level was relatively weak, little harm arose.
Today it is different. The Republicans in particular have become an increasingly monolithic European style ideological party in a system that, unlike European democracies, has no safeguards against their weaknesses for democratic rule. Further, their ideology is consciously anti-democratic, as we can see when they want to eliminate voters who, in their eyes, would vote against them. Multi-party parliaments can handle such parties far better than our current system can.
Given Republican efforts to reduce the voting populations of people likely to vote for the other party, as well as the extreme nature of their social legislation priorities (yes, both parties are corporatist but there is more that matters than that), there is a real chance that a Romney presidency would be the end of what remains of political freedom in the country. This is particularly true given the likelihood of one or more Supreme Court vacancies opening up over the next four years and the actions of the radical Republicans on the court.
What to do
Anyone who thinks it does not matter who wins because they are "all corrupt" should ask themselves whether Al Gore would have given us policies of torture, invaded Iraq, or appointed people like Alito to the Supreme Court. An honest answer would be "no." Millions of people are dead because Bush became president.
Today we have a man who appears to be a genuine psychopath running under the Republican banner, pitted against a reasonably competent tool of the corporate world. While in my mind there are no positive choices, there is an enormous difference between them. This difference is even bigger for Pagans than for most other Americans.
So what do you do if you care about the future of a free society? First, vote against the Republicans in whatever way seems most effective. Second, in states that have them, push for initiatives establishing majority elections to replace plural elections. That would accomplish three vital tasks.
First, it would make it possible for genuinely powerful alternative parties to arise because a vote for one of them would not be a vote for the major party you like least.
Second, it would encourage candidates from the main parties to address issues raised by third parties because they want those people to vote for them in a runoff. Genuine issues usually ignored will then actually be addressed.
Third, it becomes possible for a third party to make it to the runoff and, having done so, to win.
Absent that reform, we need to be aware that a flaw in our current electoral system makes us vulnerable to a deeply anti-democratic and vicious government coming to power in an American version of the dynamics that brought down the Weimar Republic.