Last winter, in the early stages of his run for the presidency, Barack Obama said he’d consider accepting public financing for the general election if his Republican opponent would do the same and agree to a set of ground rules, including limiting spending by party committees and outside 527 political advocacy groups.

That statement by Obama came before he assembled the most impressive fundraising juggernaut in modern political history, thanks in large part to an explosion of small donors giving over the internet. If Obama accepted public financing in the general, he’d have $85 million to spend between the end of his party’s convention in late August and November 4. Obama realized he could raise far more than that for the late stages of his campaign and do so in a generally honorable way. (John McCain, in turn, refused to limit spending by the RNC or referee 527 groups active on his behalf). So today his campaign announced it would opt out of public financing in the general. As the great economist John Maynard Keynes once said, when accused of inconsistency: "When the facts change, I change my mind — what do you do, sir?"

The facts changed for Obama. "It’s not an easy decision, and especially because I support a robust system of public financing of elections," Obama said in a message to supporters today. "But the public financing of presidential elections as it exists today is broken, and we face opponents who’ve become masters at gaming this broken system."

McCain predictably slammed Obama’s decision, in a calculated attempt to reaffirm his lapsed reformist credentials. Yet McCain’s the one who’s violating both the spirit–and perhaps the letter–of existing campaign-finance laws, as my colleague John Nichols noted, by opting in and then out of public financing when it was politically expedient.

Obama’s army of small donors, building on the grassroots movement pioneered by Howard Dean in 2003-2004, represents a far more compelling challenge to the status quo than anything McCain is proposing. According to the Campaign Finance Institute, nearly early half of the $263 million the Obama campaign raised as of April came in donations of $200 or less. Only 34 percent came from donors giving $1,000–not an insignificant sum, but not an overwhelming number, either. Obama has almost three times as many small donors as McCain.

Sxity-three percent of McCain donors gave $1,000 or more. Only 23 percent of the $100 million McCain raised as of April came from donors giving $200 or less. While Obama built a campaign for the 21st century, McCain is still wrapped in conventional politics, raising big donations from the usual assortment of wealthy donors and big business.

Of course, small donations alone don’t alleviate the need to fundamentally change how elections are run or financed in this country. Senators Susan Collins and Russ Feingold have sponsored legislation to modernize and update the current presidential public financing system, while Senators Dick Durbin and Arlen Specter have introduced a bill to publicly finance Congressional campaigns. Obama is an original cosponsor of both Feingold-Collins and Durbin-Specter. McCain has declined to sponsor either.

The campaign finance reform community recognizes these changing realities, but some leaders still remain wedded to the days of old. Fred Wertheimer of Democracy 21, one of McCain’s closest allies in the campaign-finance movement, said he was "very disappointed" in Obama’s decision. Public Citizen also proclaimed itself "deeply disappointed." Both Wertheimer and Public Citizen President Joan Claybrook helped to create the post-Watergate system of public financing, so they are naturally reticent at watching it die.

Other groups accept that the current system of public financing, in the words of Common Cause President Bob Edgar, "is badly outdated and in need of a major overhaul." They hope Obama, based on his past and future commitments, will be the one to change that. As one campaign-finance reformer told me, "holding Obama accountable for not opting into a broken system isn’t really fair. We want the best reformer to win, not the candidate with a hand tied behind their back."