Washington ? Within the next few weeks, two of the Democratic White House hopefuls will decide whether to join President Bush in rejecting public financing of their pre-convention campaigns, using private funds to pay for the primaries. By declining the taxpayer-supplied matching funds their less affluent rivals plan to accept, former Vermont Gov. Howard Dean, who has set the Democratic pace in contributions, and Sen. John Kerry of Massachusetts, who has family wealth available to him, can sidestep the spending limits the other seven will have to observe.

Dean and Kerry will calculate what gives them the best chance at the nomination. It is unfair to ask them to consider the larger implications of their action for the campaign finance system, especially when Bush is, again, breaking records for tapping the wallets of his supporters.

Already the system of partial public financing of the presidential race is in shaky condition. In 1996, Steve Forbes used his private wealth to become the first major-party contender to step outside the system. And in 2000, when Forbes did the same thing, Bush trumped him, becoming the first privately financed candidate to win a major party nomination. If leading Democrats now follow suit, it will clearly signal that the nearly 30-year-old experiment in partial public financing is on its last legs.

A report released late last month by the private Campaign Finance Institute, a Washington nonprofit, offers strong evidence that time has caught up to the system that was created in 1974 and used for the first time in 1976.

As the report says, the system under which “the federal government has matched the first $250 that candidates raise from individual donors if the candidates agree, among other things, to limit their spending … for many candidates is no longer worthwhile. Accepting spending limits has become too risky and public funding has become less valuable. And to top it all off, the whole public financing system faces the real threat of insolvency by 2008.”

The group’s bipartisan commission, made up of experienced politicians and first-rate academics, argued that “a collapse of public funding would be a real loss for democracy. The system has helped to support competition, restrain costs and enhance the value of small contributions. If the system were to be lost, the only winners would be front-running or wealthy candidates who can manage to get their own messages across without any help. The initial losers would be other candidates whose presence promotes competition and civic dialogue, but the real losers would be the American people.”

So far, at least, major party candidates all have accepted full public financing of their general election campaigns, with the spending limits attached. But the report makes it clear why the nominating system is in trouble. What was once a relatively leisurely schedule of primaries, allowing candidates to raise money as they go along, has become a truncated, front-loaded contest, requiring far more money in hand at the beginning of the year. The presence of privately financed or self-financed candidates makes the odds against the publicly subsidized contenders even worse.

The other part of the problem is the growing scarcity of funds for the public subsidies. They come from voluntary checkoffs on income taxes. The maximum for an individual has been raised once, from $1 to $3, but the percentage of people designating any of their taxes for this purpose continues to decline. The commission says that if candidates in both parties accept public subsidies in 2008, the fund would likely go broke.

Its recommendations are admirably straightforward. To encourage more candidates to accept public financing, it would double the spending limit for the primaries to a sum equal to the roughly $75 million allowed for the general election; allow a publicly subsidized contender to spend as much as the most free-spending candidate who relies entirely on private funds; eliminate the state-by-state limits, which simply invite cheating and which fail to recognize the importance of early contests in states such as Iowa and New Hampshire.

To increase the incentives for small contributions, instead of a 1-1 match for the first $250 donation, the commission would make it a 3-1 match for each $100 gift. And to replenish the fund from which subsidies are paid, it would increase the individual checkoff limit to $5.

The final point in this admirable report is a reminder that to be in place for the 2008 campaign, the changes in the law should be made in 2005. Congress should put this on its “to-do” list.

David Broder is a columnist for Washington Post Writers Group.