In that case, you’re best off opting out and seeing if it works. If you get a text from the same group at a later date, then you can report them to the FTC. Please do not do this unless they do not honor your opt out request, as politically affiliated groups are legally allowed to market in this way so long as they provide a means to opt out of communication. Falsely reporting puts strain on the already incredibly underfunded system and prevents real scams from being caught and dealt with due to a lack of resources. I recommend you keep a list of groups you have opted out from that is easily searchable to track this. 4 years ago I got multiple of these texts per day. I have been opting out every time I receive one, and now I have not gotten one in over 2 years. Eventually you will run out of groups to opt out of, and will only be messaged by newly created groups, which will happen much more slowly than all of the groups constantly texting/calling.
Beyond that, there isn’t really much you can do. Your number is on a list, and people are buying that list. Although you could see if putting your number on the national do not call list would help (EDIT: though apparently political organizations are exempt from that on further reading). I have not done this personally, but I came across it while looking up how to report scam texts. Perhaps it could be beneficial to you (who knows?)