The New York State comptroller, Thomas DiNapoli, has proposed an excellent way to clean up the costly and tainted campaigns for his powerful job. He has submitted a bill that creates the state’s first voluntary public campaign financing system, which would apply only to his office. To clean up Albany’s muck, the state needs a much broader system. But this is a start.

The comptroller acts as sole trustee of the state’s $141 billion pension fund. And as we saw in the Hevesi scandal, contributors are eager to trade campaign contributions for a piece of the investment business.

The Securities and Exchange Commission has since barred anyone from conducting business with a state pension fund for two years after contributing to a comptroller candidate. The DiNapoli bill, which would go into effect for the 2014 elections, would take the next step.

It would encourage small donations and help less-than-wealthy candidates by matching the first $250 of each contribution with at least $1,500 in public funds. Participants would have to raise $150,000 across the state to be eligible, and the limit per contributor would be $2,000.

New York’s extremely lax campaign finance system allows individual contributors to give $19,700 during the primary to a candidate in a statewide race and an additional $41,000 in the general election. In the comptroller race last year, Mr. DiNapoli spent $4.09 million; the Republican candidate, Harry Wilson, spent $6.97 million.

The Legislature should pass the bill swiftly and Gov. Andrew Cuomo should sign it into law. They can’t stop there. New York needs full campaign finance reform.