Democrats have been doing this since forever.
Our side needs to set up tables in public places, hand out blank registration forms.
MOST IMPORTANTLY, remind people that if they have moved, their registration may have been purged. Or their voting precinct location may have changed. So they need to check their status with their past registrar; they need to clear up any confusion BEFORE November.
Or they are still registered at the old address, the RATs know they have moved and fraudulently vote their ballot.