And yet, only 50% of the population votes! I continue to believe that we should differentiate between the stated/perceived and the effective differences between the parties, and far from being dumb, the public is aware of this difference, and that the effective differences are small but significant in the context of what is possible. While I am greatly impressed with Michael Smith's points, I think Woj, and Julio, pretty much summed the issue up accurately (though I do not agree that Woj's (a) -- structural limits -- is obviously untrue). The Dems are the only vehicle (on two fronts: it exists and it is the only one that does, and it does share a significant part of the goals) for the aspirations of a lot of people, and given the amateur politicking of the blogistan and the circular firing squad mentality of the "left", there will be no alternative in the near future.
So, even if the Dems need to be destroyed, they should be destroyed from the inside. I believe there is nothing new in all of this -- the right-wing has given us the blue-print in their successful take-over of the GOP.
--ravi