A very good argument for the need to participate within one of the two major political parties was posted in a comment thread at Electrolite. I'm still not persuaded, mind you, but it made me pause and think.

When I was in school, and they taught me Civics, I was led to believe that the "right" thing to do was vote for the candidate, despite party. I was led to believe that parties were primarily engines of corruption such as Tammany Hall. This would have been late Seventies, in case it matters.

I think that my Civics teachers were good people, and that they taught me what they thought was clear and true. I also think that what they taught me is pravda which serves to divide people from each other so that they are less powerful. The fundamental truth of politics (as well as life, but let that go) is that things get done by organizing groups of people. Americans think highly of individuality, and I would never argue that individuals are powerless, but no single person has the power that one hundred organized people do.

[...] You won't ever find a party that fits you to a T. People being people, you're unlikely to find a candidate that does, either, of course. However, don't just look at the candidate. Look at the party. Look at the type of people they've been supporting for election, lately, even if those people haven't won. Look at their platform. Look at the planks that everybody knows are extremist nonsense that will go by the board and think about what constituency those planks are there to pacify. Look at the people currently serving that belong to that party, and their patterns of behavior. There's plenty to hate in both parties, but it matters. "The difference between bad and worse is often more important than the difference between good and better," to approximately quote Heinlein.

[...] I'll finish on a personal note. When the House was considering impeaching President Clinton, I listened to the Committee Hearings compulsively. All day, every day, for days and days. I was asked repeatedly why I bothered. After all, they weren't saying anything new. That is more amazingly true than I can express. For all that, I found it enlightening. The process and the rhetoric frightened me in a way that the daily news reports did not. After several days, I vowed that I would never vote for another Republican again for as long as I live. It became clear to me that the Republicans were making an attempt to unseat a duly elected president by unfair means, and that they had absolutely no respect for the government or the rule of law. I've seen nothing since then to disabuse me of that judgment.

(I included the last paragraph just because I agree with it so strongly. Even if I were to move back to New England, I don't think I could vote for a Republican for the foreseeable future.)