Barry Commoner on the Citizens Party ticket in 1980 is more the model I am thinking about. I don’t dispute that Obama, in this area as in many others, is an outlier. Having gone door to door for most Democratic candidates since Carter, I got the sense as an environmentalist that he and Gore were the ones who were most serious about it. I don’t think the party as a whole prioritizes it enough.
I don’t know why you went down to the Senate level – I doubt Greens run in SC, but I’m not sure my argument even begins to work unless the third party can influence the major parties and bring independent ideas into the process and public consciousness. I’m not sure one could even begin to argue that for state races.
Too often when talking about challenges to the party or its frontrunner, the effect at the ballot box is the only thing that counts. But elections are much more complex. I realize Sanders did not go the third party route, but I think that he exemplifies the way in which a candidacy can affect the race prior to the final vote count. And one effect can indeed be to throw the race – I just don’t think that is the only one or that the causality is always clear.