Think back.
Who with the GOP/RNC did you interact with using your cell phone?
OR
Who with the GOP/RNC did you give your cell phone number to?
I only use my cell for making the occasional phone call or text to an individual, most likely someone I know. No social apps and I don’t give out my number to companies. All I get is the occasional and very random spam. text. Nothing focused on my interests or habits.
Location Services aka GPS tracking is always off. I’ve removed as many apps as possible, disabled as many others as I could and went through the rest and denied as many permissions as possible.
GOP/RNC may be getting info from voter registration. Also many places sell phone numbers. Club cards etc.
Stores ask for phone numbers or even e-mails on simple purchases. From Home Depot we have; “would you like an e-mail receipt?”