The most commonly talked about reform is a constitutional amendment, but that鈥檚 a long shot. In Massachusetts, Republican incumbent Sen. Scott Brown and his likely challenger, Democrat Elizabeth Warren, just signed an agreement 鈥 The People鈥檚 Pledge 鈥 to persuade super PACs not to participate in their closely watched race. It鈥檚 unclear how such a cease-fire could be enforced.