It's true that the Democratic caucuses, both federal and state level, are much harder to hold together. Every year there's a bill in my state to reign in pay day lenders. Basically banning usury level interest rates on loans. Overwhelming popular support (~80%) and editorial support.

And every year there's a "blue dog" Democrat living in a purple district which bends to the pro pay day loan lobbyists.

Vetocracy is a tough problem. Our civic legacy is to fear the mob, tyranny of the majority. (Thanks Plato.) So it's rare that mere popular support ( >60%) is sufficient to attain progress.

So, to your point, mere 50% + 1 vote ain't ever enough.