"Would campaign finance reform require a constitutional amendment?"Short answer, it depends on what you mean by "campaign finance reform". Its like ex-Navy SEAL Richard Machowicz's great saying: target dictates weapons, weapons dictate movement.If what you want is to limit free speech rights (which as the Supreme Court interpretes it) means, essentially the right of any individual or corporation to spend whatever they want on a political race, that requires a constitutional amendment. Which, to pass, requires 2/3rds of both Houses and 3/4ths of the state legislatures to approve-- THAT is like hand-towing a howitzer up and down a mountain.The Supreme Court has allowed clean money schemes like Arizona's where candidates can voluntarily limit their own campaign fundraising and, in exchange, they receive a stipend from the state (or perhaps someday, the Federales) to fund their campaign. The idea is you can't turn down the volume of bought candidates, but you CAN turn up the volume of clean candidates. Passing a bill that appropriates money in this way must pass both Houses of Congress and to get through the Senate will need 60 votes. After which, the appropriation must be renewed annually. Now you're making progress, you have a mule train to haul the artillery piece.A I suggested to Larry Lessig a couple weeks ago, you could turn the last proposal inside out and gave a tax credit to the campaign VENDORS of clean money candidates (e.g. TV station who ran ads at no cost to candidate would be given a tax credit equal to the fair market value of an equivalent ad buy). That bring you into the world of tax expenditures, which have two unique properties. 1. Tax bills can pass the US Senate with only 50 votes (plus VP tiebreaker) by using the filibuster-proof reconciliation process. 2. Tax breaks don't have to be renewed annually like appropriations. Once they're on the books the inertia of the system makes them tough to repeal. That route is like a helicopter hauling your howitzer over the mountain.Clearly the first step is to figure out (if at all possible) how to achieve your goals through the tax code. The idea is tax activities you don't want (e.g. tobacco sales) and give tax credits to activities you do want (e.g. hiring disabled veteran).