It's not just money, it is also a certain block of voters that appears in almost every state. The two are not necessarily connected.
The Democrats have a certain block of voters that form its establishment as well, and they appear in most states too. Same thing with money. These two are not necessarily connected either.
The difference between the Republicans and the Democrats, and the reason why establishment Republicans tend to control party nominees moreso than Democrats, is because the Democratic establishment and its "moneyed base" have been less likely to align than the Republicans, respectively. That often is the case because their interests are at greater odds with each other than in the Republican party.
I'm not going to tell you who they are - that's for you to figure out on your own.