- never signed up for anything like this,
- never donated to or signed up for emails from the DNC, et al.,
- political texts like this come all the time, and
- I hesitate to reply “stop” because I don’t want them to know this is a live number (is my instinct here outdated/inapplicable?)
Most don’t get that many. OP is likely targeted in the systems. My guess is that he votes often in the primaries and has shown interest elsewhere, like by signing up for communications or donating to or volunteering for campaigns.
I just checked my spam and I’ve received four political texts in July.