There is already a proposed constitutional amendment in the works to do just that, among various other measures at the state level, and it already has state approval for ratification by twenty-five of the necessary thirty-eight to pass.

Essentially, Citizens United and other corrupt rulings like it operate on two legal grounds: making artificial entities (groups, PACs, corporations) legally the same as individual citizens with the same protected rights such as free speech, AND barring states from limiting the amount of cash that flows into the elections they constitutionally control. This amendment addresses both of these legal bases.

Here's the text of the proposed amendment:

Section 1. We the People have compelling sovereign interests in the freedom of speech, representative self-government, federalism, the integrity of the electoral process, and the political equality of natural persons.

Section 2. Nothing in this Constitution shall be construed to forbid Congress or the States, within their respective jurisdictions, from reasonably regulating and limiting contributions and spending in campaigns, elections, or ballot measures.

Section 3. Congress and the States shall have the power to implement and enforce this article by appropriate legislation and may distinguish between natural persons and artificial entities, including by prohibiting artificial entities from raising and spending money in campaigns, elections, or ballot measures.

I know it's hard to believe, but getting big money out of politics really is a bipartisan issue. It keeps good people out of office altogether and the rest unable to address the power of cash concentrated in a very few hands.

If your state isn't already on this list, look it over and see if it's something you can support. It needs to happen not just with an amendment, but at all levels. Every bit helps.