http://www.dailykos.com/story/2016/...s-The-Current-State-of-the-Democratic-Primary
This is actually a really good piece of analysis of the numbers behind the Dem race and I encourage everyone to read it (dailykos, I know, but it's a genuinely good article). Basically all data, no punditry, and I fucking love how they use a least resistance model and not uniform swing. Explains all the critical stuff - Nevada is the key state, not SC; what demographics Clinton needs to protect most and Sanders needs to win over most; etc.
The Dem primary most-swingy state is Michigan. Nevada is somewhat Clinton-favourable, but not particularly strongly so. Iowa and Nevada are the two key states. If Sanders loses Iowa, he's out of the race. If he wins Nevada, he's the front-runner. If he edges Iowa and Clinton edges Nevada, we have a fight on our hands. In South Carolina, Sanders need to lose by less than 19% to stay in it, and 15% means he's doing well enough to win.