Nope, in the US you register with the state and you can optionally tell the state that you are a member of some party. You can register to vote and self-identi

Nope, in the US you register with the state and you can optionally tell the state that you are a member of some party. You can register to vote and self-identify as 'Dem' 'Republican' etc while getting your driver's license. Aside from the public voter file update, the Democratic Party doesn't get any special notification if you pick them, and you don't need to apply or get accepted in any way.