Establish by law that money held by a corporation is legally owned by the shareholders, who own the company, or employees, who earned it, and no money can be used by the CEO or board of directors for any purpose not directly related to the core function of the corporation without approval of those whose money is being spent.
Officers must specify amount of spending proposed and what issues, politicians or party is to be supported. Unapproved spending shall be theft.
Approval must be given by voting and those not wanting their money spent on issues or politicians of which they disapprove receive their share of the proposed spending as additional dividend or wage bonuses.
This will lessen disastrous aspects of the Citizens United SCOTUS decision without tampering with Constitution.