Over on Midwest Bloggin, I tried to post a long comment on why I don’t think it makes sense to vote for a third party. (Note to those who voted for Nader instead of the Democratic nominee: please do it again, and encourage all your friends to do so as well.) But my comment was too long to fit, so I’m putting it here.
If you look at the history of parties in the United States (at least at the presidential level), there has never been a third party that gradually grew to become a major party.
No new party that did not elect a president within its first two tries has ever done so.
The last successful third party was the Republicans, who were founded almost 150 years ago.
Why did the Republicans succeed? Because despite the strength of anti-slavery sentiment among the population, neither the Democrats nor the Whigs were willing to adopt an explicit anti-slavery platform. The Whig Party collapsed. The Republicans took second place with 33% of the vote in 1856, and won the presidency four years later.
Why have there not been any successful third parties since 1860? There have been some strong third-party showings during that time, but whatever issue gave rise to the third party either faded quickly or was co-opted by one of the major parties. (For example, the centerpiece of Ross Perot’s 1992 campaign was the deficit. By the time the ’96 campaign came along, deficits were going down, so Perot’s issue was fading. One reason they were going down was that the Republicans in Congress had co-opted the issue.)
The only time since 1860 that a third party has taken second place in a Presidential election was 1912, but that was a special case: former Republican President Teddy Roosevelt ran on the Progressive Party ticket and took second place with 27%. Four years later, without Roosevelt, the Progressive Party couldn’t even get into double digits.
The major parties have learned the lessons of history about third parties, and whenever a third party looks like it’s getting somewhere, whichever of the major parties is closest to the third party will move to attract the voters of that party.
It’s the instinct of self-preservation: neither the Democrats nor the Republicans wish to end up where the Whigs are today. (When’s the last time you met a Whig?) That’s why I believe it’s extremely unlikely we will see a successful third-party presidential candidate in our lifetimes. (And if we do, I think it would almost have to be celebrity-personality-based, not a matter of a successful new political party.) Perot was the closest, and he got less than 20% of the popular vote, and not a single Electoral College vote.
So, voting for a third party can have an influence on the policies of the two major parties, but it is unlikely to elect your candidate (unless the candidate is a celebrity, such as Jesse Ventura.) BUT, a third-party candidate who gets a substantial share of the vote is likely to cause the major-party candidate closest to your own positions to lose. (Liberals voting for Nader over Gore allowed the election of George W. Bush.)
That is why I think it’s best to work within the major party that is closest to your views rather than through a third party. Use the primaries for statements of principle, but be pragmatic in the general election.