At first I thought each individual state's party decided how to do the primaries for themselves, as private organizations.
But then I read that elections in some states are organized by the government, not the party.
If I created a new nation wide political party, would I be able to hold the primaries however I wanted, for instance by using some obscure Condorcet method, or in some states I would be required to use some preestablished rules? Which are such states and what are the rules?
What about the national convention? Is there some rule specifying how the states primaries results should be computed? Instead of having delegates, could my party simply sum all the individual votes from every state to get a simple majority?