Didn't Socialist Action give at least some sort of endorsement to basically all the socialist presidential campaigns running last year?
Agreed. Most of the groups that call themselves parties these days are mainly parties in the sense that they run candidates (as my organisation, the
Socialist Party USA does), but no group that exists today. Furthermore, there's no group that I could argue for as being a nucleus or precursor for a future revolutionary party. Amino acids that may eventually form the nucleus, perhaps, but that's painfully extending the metaphor.
The question then, I think, is what to do under these conditions? I'd argue that one of the best courses of action is to try to keep an open dialogue among different organisations, try to find common areas of agreement where joint work can be done, and attempt to be honest and frank about political differences. Also, while no one would blame you for trying to recruit people to your own specific organisation (because we want to see them grow, dammit), the more important point is to get more people involved and active as revolutionary socialists.