A few different things contribute to this and, unfortunately, there’s very little you can do to fix it. I’ve spent (wasted) a ton of time trying to prevent it on my end.

1. If you used your phone number on your voter registration, reregister immediately without your phone number. This is public information and it’s where these things start.
2. Find contact info for your local, county, and state parties. All sides. Call them up and ask that your information be removed from their database(s). You might have to escalate a bit because usually phone bankers don’t know how to do it or don’t understand why you want privacy. Worst case scenario you can pull out a sob story about an abusive ex and how your information isn’t supposed to be public at all. That will usually get your shit pulled.
3. While you’re on those calls, try to find out where they either send or pull their data from. Next go there and do step 2 again.
4. Repeat step 3 as many times as it takes.

However, individual candidates who may have received a copy of your data or canvassed you might not get the notice. Eventually their copies of your data might get leaked. You have no control over this and no recourse. I know this from personal experience. Through a unique mixup with a name, I have slowly watched my data go from politician to politician to now general spam. It’s not coming from data brokers because the only place the mixup happened was with political data.

Best of all, the FTC doesn’t give a shit. If someone “manually” sends you a political text, it doesn’t require prior consent. The “manual” setup for this is a bunch of VoIP shit that doesn’t actually go back to a real human ever and is about as “manual” as the fully automated assembly lines from How It’s Made where a human is standing nearby with a clip board saying “yup that’s a widget.”