Here are the things people may or may not mean when they say "Republicans":

- Current elected officials in the national party
- The national party's registered and active members
- The national party's registered members, active or not
- The national party's formal leadership
- All of the above, except at the state or local level

- People who voted for a party candidate in the last election
- People who voted straight ticker for the party in the last election
- The above two, except for "the past several elections"

- Voters who self-identify as being "with" the party
- Voters who sympathize with the party's positions
- Unelected public officials / appointees / staff who work in a party administration
- PR people working for the party
- Party-sympathetic pundits who go on TV / radio
- Party-sympathetic commentators and broadcasters who have their own programs
- Donors to the party
- Lobbyists
- Random people on social media who talk about the politics of the party

All of these have equivalents for other parties, of course. Be precise in your language!