I think a lot of people are looking at Ron Paul as being against the Iraq war and then paying about two seconds of attention to the rest of his platform. The whole "less government" thing sounds nice until you look at what he actually believes. When he doesn't win the nomination, those people are going to vote Democratic, since it's the only remaining anti-War vote.

The Democratic Party has long been a fairly loose coalition. It's part of the reason that the party has such a hard time; people seem less likely to meet some notion of what the party believes than on the Republican side. That's not to say that there aren't differing beliefs on the Republican side, but they seem to put aside their differences to form a united front more easily.

That said, there are a huge number of factions in the Republican Party in a way that doesn't really exist in the Democratic Party. The Dems have this wide spectrum of beliefs, whereas the Republicans seem to have a handful of different sects. You've got your neo-conservatives that seem to have dominated the party for the last ten years or so. You've got the evangelicals and other social conservatives, on whose shoulders the neocons seem to have ridden. You have a few libertarians. And then you've got the occasional paleoconservative. Few of these groups have many significant commonalities. But they have banded together to gain an upper hand. But their cohesion is failing. While the Democrats have dealt with the wide array of beliefs for quite some time, this is fairly new to the Republicans, and they don't seem to be holding it together very well, especially since the actions of the neocons have roundly failed at virtually every aspect. Not a very good star for the other groups to hitch their wagons to any more.