Originally published in the New York Times' Room for Debate.

The Senate’s failure to respond meaningfully to the Newtown massacre was deplorable, but the real tragedy is that it was utterly predictable. In our "show me the money" political system, special interests and their armies of lobbyists call the tunes. Congress will continue ignoring the issues that matter most to Americans until we fundamentally change the role of money in politics.

Gabrielle Giffords, the former U.S. representative, was absolutely right: the minority of senators who blocked common-sense reforms did so based on “political fear and on cold calculations about the money of special interests” like the National Rifle Association. Last year, the N.R.A. outspent the leading gun control lobby 73 to 1. Senators facing tough re-election campaigns ignore the wishes of 90 percent of Americans because they fear the gun lobby could mount a $9 million ad campaign against them.

The Supreme Court’s hostility to reasonably regulating money in politics culminated in Citizens United, which opened the door to unlimited spending by outside groups. Since 2000, while candidate spending increased by 91 percent, spending by outside groups increased by nearly 2,500 percent. This has produced a dramatically tilted playing field on which moneyed interests easily bend elected officials to their will.

Now, wealthy interests don’t even need to spend their money to buy results — the mere threat of a super PAC attack campaign can do the trick. Elected officials will never have the courage to stand up to these groups until they have a way to campaign that doesn’t require them to dial for dollars from the same deep-pocketed donors fueling the outside spending.

The solution to this political dysfunction is to empower regular voters as a counterweight to big political money. The Empowering Citizens Act, sponsored by Representatives David Price and Chris Van Hollen, would do precisely that. By matching grass-roots donations from regular voters with public funds, the system would give Congressional candidates an alternative path to victory in which they depend on constituents and voters, instead of deep-pocketed donors seeking political favors. Such a system would give officials the courage to stand up and act in the public interest, not on behalf of the special interests.

The N.R.A.’s defeat of measures with overwhelming public support is just the latest proof that if we want better public policy, we’ve first got to change the process of our politics.