Ad to this the reality that many of the above number would actively or passively aid the constitutionalists and the fact that they are widely dispersed throughout the country and constitutionalists would easily carry the day. That's not to say that there wouldn't be casualties. But that the outcome would be easily decided.
There won't be a CWII, the left will turn on themselves long before we get there. The biggest problem the left has in such a scenario is that they are not self reliant. Their urban environments they created are not substainable, they produce nothing there. We can live without them, while they are dependent on us for food, power, etc.
All we would have to do is turn off the power or water (which are in "red" areas) and wa-la, sundown day number 2, the riots begin. Actually we don't even got to do that as some of their own policies (i.e. Cap and Trade) will end up doing it for us.
Why fight them, when we can just sit back and watch them take each other out.