This is what I've been wanting to say to you, but I could never quite get it put together. Fortunately, Erik Loomis says it better than I ever would have.
I would like to think that we on the left actually do understand history. We do not. There is a clear path to change. Conservatives understand this. You take over the party structure. That’s what they did in the 1950s and 1960s when they were disgusted by the moderate Republicanism of Dwight Eisenhower, Earl Warren, and Nelson Rockefeller. They took over party structures and local offices and turned them into bastions of energized conservatism. Note that conservatives basically don’t run 3rd party campaigns. Libertarians might talk about doing this–but they almost all vote Republican in the end because they know that they are moving their agenda forward by doing so.
Any reading of history shows that change within the American political system does not come through third party campaigns. It comes through the hard work of organizing our communities to demand change.
At times, a 3rd party could theoretically make sense. The last one that made any difference was the Populists.
If Teddy Roosevelt couldn't build a lasting 3rd party, none of the people running today can possibly accomplish it. Organizing is hard work. If you're unhappy with the way Obama is governing, or the way both parties are funded, you need to do the hard work of organizing a movement that cannot be ignored by politicians. And you need to gain control of one of the already existing parties -- which enjoy huge structural advantages over third, fourth or fifth parties in terms of elections. That's the way the extreme conservatives took over the party of Eisenhower and Reagan and it's the only way that's been shown to work in American politics for the last 150 years or so.
I'm sorry, but this is the reality of history.
It may feel good to vote for a near perfect candidate with no chance of ever winning, but it is a very counterproductive way to achieve the change you want. And I hope you'll give this another consideration before casting your vote, because I want the same change you do, and I know beyond a shadow of a doubt we will be light years closer to the country we want with 4 more years of Barack Obama than with 4 years of Mitt Romney.