U.S. Sen. Barack Obama, the presumptive Democratic presidential nominee, has turned down public financing for the general election and chosen to carry out his campaign relying on money he raises. Sen. John McCain, the presumptive Republican presidential nominee, will accept public funds. Last year Mr. Obama pledged to run under the public campaign finance system in the general election if the GOP candidate agreed to do likewise. The system imposes spending limits in return for a $84.1 million federal campaign subsidy.

The Obama campaign has so far raised some $290 million, thanks in great part to small donations from individuals made via the Internet, while the McCain campaign has netted about $120 million in donations. The most likely factors behind Mr. Obama's change of heart is the prospect of donations continuing to pour in and his desire not to be bound by spending limits. It is not surprising that he was accused of falling short of his own lofty standards when he made it clear that he was going back on his word.

Public campaign financing was introduced in 1976 in the wake of the Watergate scandal. Since then both Republican and Democratic candidates have accepted public financing for the presidential general election campaigns through 2004. Mr. Obama will become the first presidential candidate from a major party to opt out of the system.

Mr. Obama declared the public campaign finance system to be "broken" because of loopholes. So-called 527 groups, registered under a section of the tax code regulating independent spending, can skirt controls on political funds and raise money unhindered by limits.

But if Mr. Obama continues to raise money through private donations, the possibility grows that he will accept money from special-interest groups, further damaging his image in the eyes of some voters.