Why is it necessary to give them your number if you do a donation? It seems many here have the same negative experiences.
Is it an optional field? If not one could practically enter any digits or can one get punished for that?
Actblue requires a phone number and email address.
As far as I know, physically mailing a check is the best way to avoid sharing information as you only need to provide your name, address, and employer. This information is the only federally required information.
Your phone number and e-mail address are more valuable to ActBlue than that $20 was.
The credit card input screen was just there to make you feel comfortable consenting to endless SMS texts for life.