Speculation: voter rolls are public, so everyone knows you’re a voter and what your registered party is. Since you voted early the state must record that. Don’

Speculation: voter rolls are public, so everyone knows you’re a voter and what your registered party is. Since you voted early the state must record that. Don’t they release counts of how many people have voted so far? Plus they would need to record you voted so they could reject any other ballots from you that might come in. There is probably a record of which elections you’ve voted in (though not how you voted). There is in my state and with some basic info I believe I can look anyone up, not just myself. So if your party has a list of their registered voters (they do, public information) then they could easily check the status to see if each of those voters has voted yet (public information). Combine that with your phone number from public records or maybe a past donation, and they’d have everything they need.