Obama's decision could also hasten the end of the post-Watergate campaign-financing system that has leveled presidential playing fields for more than three decades. Both major-party candidates have opted into the public campaign-finance system since it was put into place in time for the 1976 elections.
The system — which relies on money from taxpayer check-offs selected by fewer than 10 percent of tax filers — has been widely criticized in recent years, and both McCain and Obama have expressed interest in making revisions.
"When at least one candidate isn't taking money at all, and 90 percent of taxpayers aren't paying into the system, you know something's wrong with the system," said Massie Ritsch, a spokesman for the Center for Responsive Politics, which tracks political spending.
Bob Bauer, the Obama campaign's general counsel, told reporters in Washington Thursday that Obama would push to update the system in time for the 2012 elections.
"That architecture has to be revamped," Bauer said. "There are … measures to do just that for both the primary and the general that I think will restore its viability as a vehicle — make it attractive — and bring candidates back to public funding beginning in the 2012 presidential election."
Obama has already shattered monthly campaign fund-raising records, and is on pace to obliterate all previous markers. He has raised more than $250 million just through the end of April for his primary campaign.
With nearly half of his money coming from donors who've given less than $200, he can tap most of his 1.5 million donors repeatedly before they reach the maximum of $2,300 each. That's not even counting the pool of Hillary Clinton donors available to him now that she has left the race.
Obama's spending could reach a saturation point: Even corporate giants know there's such a thing as too much messaging to throw at consumers. Both candidates will get wide press coverage throughout the campaign, and such "free media" can be just as important in an election's outcome.
The McCain campaign is hoping Obama's decision will tarnish his image as a reformer. Obama committed publicly to pursuing an agreement with McCain that would involve both of them taking public dollars, only to abandon it less than two weeks after he became the presumptive Democratic nominee, with Clinton's exit.
"This election is about a lot of things but it's also about trust. It's also about whether you can take people's word," McCain said Thursday in Iowa.
The candidates' spending doesn't tell the whole story, since other organizations chip in. Republicans will be able to compete financially through the auspices of the RNC — which has done a far better job raising money than its Democratic counterpart — and outside groups, which played a major role in 2004 and are already spending this year.
But, Goldstein said, a critical difference will be that the Obama campaign will have full control of its resources, while the McCain campaign will have to lean on outside groups with which it cannot, by law, discuss strategy or messaging.
"It not only gives him tons of money, more importantly, it gives him tons of control," Goldstein said. "Obama can freeze the race. It can put so much money up there that it spends McCain into oblivion."