You grow a texting list the same way you earn any trust: ask clearly, deliver on the promise, and keep asking. Every supporter touchpoint is an opt-in opportunity if you add a clean call to action. The size of your list at GOTV is a function of how many of those you set up months earlier.
Where the opt-ins come from
A text-to-join keyword on every sign, slide, and flyer; a sign-up field on your website; a checkbox on your donation and volunteer forms; a keyword at events and the door. Each one needs the proper disclosure, who's texting, what they'll get, reply STOP, so the consent is documented.
Make the promise specific
'Get updates' is weak. 'Get election reminders and ways to help' tells people what they're signing up for, which both raises opt-in rates and lowers opt-outs, because the messages match what was promised.
Frequently asked questions
How do campaigns build a text opt-in list?
Through a text-to-join keyword, website sign-up, and consent checkboxes on donation, volunteer, and event forms, each with clear disclosure. Collect continuously, not at the last minute.
What's the easiest way to get text consent?
A text-to-join keyword ('Text JOIN to…') promoted everywhere, plus opt-in checkboxes on the forms supporters already fill out. Keep the record of each opt-in.
Informational, not legal advice.
Keep reading: How to grow a texting list that's actually yours and The call to action: what a compliant opt-in looks like.