Campaign reform advocates grappled with the possibility that a constitutional amendment might be their only remaining option to limit the power of money in politics in the wake of the U.S. Supreme Court’s landmark April 2 ruling in McCutcheon v. Federal Election Commission.

“It won’t happen overnight, but we have to move forward with a constitutional amendment,” said John Bonifaz of Free Speech for People, one such group. “Congress has to have the authority to enact reasonable limits.”