- 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- I hesitate to reply “stop” because I don’t want them to know this is a live number (is my instinct here outdated/inapplicable?)
That looks like a desktop app. You can send SMS from your non mobile computer?
It seems to be the SMS integration that MacOS can have when you also own an iPhone.
You can do the same on Android on any other operating system