As a non-USAian and not a lawyer, what is the difference between power and speech? Isn't removing the power to "speak" (donating money) not an infringement on "free speech"?
Edit: The article OP shared helped
Doesn’t this violate Citizens United?
No. As Dean Soifer put it: Citizens United “struck down a federal regulation that prohibited an already-empowered corporation from spending its resources in elections. Neither that case nor any other has addressed whether a state must grant political spending power in the first place.”
It's like bring born without a mouth: you can't speak so there's nothing to prevent --> no infringement on "free speech".