The era of “super PACs” and secret donors has made public financing more urgent. A system that greatly magnified small donations with high matches would give ordinary citizens a shot at competing with corporations, unions and wealthy donors. It would allow candidates to campaign more instead of constantly begging among the rich. And it would give a challenger a chance to be competitive without the help of a super PAC.

Ronald Reagan could not have challenged President Gerald Ford for the Republican nomination in 1976 without accepting public dollars. The system also made campaigns possible for such diverse candidates as Jimmy Carter (1976), George H. W. Bush (1980), Jesse Jackson (1988) and Pat Buchanan (1992), all of whom had essentially run out of cash against opponents with much more money.

There is nothing conservative or liberal about public financing, which allows any kind of political voice to be heard above a roar of cash — if lawmakers are willing to spend more. Here are several ways that Congress could revive the system:

Raise the grant The biggest reason candidates are dropping out of the system is that they can raise much more money outside of it. This year, Mr. Romney and Mr. Obama could get $91.2 million each from the Treasury if they participated in the system for the general election, and that is all they could spend. In 2008, Mr. Obama and his party raised about $750 million. He and Mr. Romney both expect to do better than that this year, and that does not include the $200 million or so to be spent by super PACs and other independent groups.

The grant needs to be doubled or tripled. A House bill proposed by two Democrats, David Price and Chris Van Hollen, would give general-election candidates $50 million, plus up to $150 million more based on a 4-to-1 match of donations of $200 or less. There would be no spending limit, but individual donations would be limited to $500. (Currently, for candidates not participating in the system, donations can go up to $2,500 in the primaries and $2,500 in the general election.)

The $200 million in the bill may not be attractive enough to candidates. While it would never equal private fund-raising, a grant of $300 million for each party could allow very competitive campaigns, and might appeal to candidates eager to spend less time raising money.