The only other practical way that Corporations can be stopped from controling all elections is.... ta d
A constitutional ammendment made in the House and voted in all 51 states by a 2/3 majority.
It takes longer but that is the straight forward constitutional option.
This ammendment to curb goverment by corporate power is much more important than hunting down gay people who wanted to marry. *The last time a constitutional ammendment was to prevent gays from ever marrying. Bush used it as red meat for the base.