the Democratic party is, kind of ironically, run like a republic. Registered Democrats at the precinct level elect representatives at the county level, who in turn elect representatives at the state level, who in turn elect represents at the national level (the DNC).
Each state elects several members of the DNC (I think there are five from Florida). Democratic elected officials holding Federal office (Senators and Reps) are also members. You can get a list at
www.drafthoward.com Each state decides how to elect DNC members, so they do it differently. In Florida, the are elected by State Committeemen and State Committeewoman. There is one of each from each county and they have weighted votes based on the number of registered Dems in each county and the Democratic performance in the last election. State Committeemen and women are elected by precinct committeemen and women (one of each from each precinct unless there are more than 1000 registered dems and then there are two of each). These are elected by all registered Dems in a precinct during the primary election.
Someone else has a thread about California and how they elected state representatives there.