At the link, Democrats propose an amendment to the U.S Constitution reversing the Citizens United case, in what would be the rare case of the Congress amending the Constitution to restrict free speech.
The proposed amendment, which was co-sponsored by fellow Democratic Sens. Tom Harkin of Iowa, Dick Durbin of Illinois, Chuck Schumer of New York, Sheldon Whitehouse of Rhode Island and Jeff Merkley of Oregon, states that both Congress and individual states will have the power to regulate and limit the amount of campaign contributions to candidates running for elected office. It would also regulate and limit independent expenditures — such as those from Super PACs — made in support or opposition of candidates and would allow Congress to pass campaign finance reform legislation that withstands constitutional challenges.