Washington ? Barack Obama’s 1.5 million donors were a financial spigot that was just too rich to shut down.

The Democratic presidential candidate on Thursday became the first presidential candidate from a major party to bypass public funds for the general election since the Watergate era. In so doing, he abandoned his once-stated desire to compete within a system designed to reduce the influence of money in politics.

His Republican rival, John McCain, said he would accept the public money for the fall campaign – $85 million available from early September until Election Day – and declared that Obama had broken his word.

Obama, who has shattered fundraising records during the primary, is likely to raise far more than the taxpayer-financed presidential fund can supply.

Obama promptly showed off his financial muscle Thursday with his first commercial of the general election campaign. The ad, a 60-second biographical spot, will begin airing Friday in 18 states, including historically Republican strongholds.

The Illinois senator has called for public financing of campaigns in the past, but while his new decision opens him to charges of hypocrisy from Republicans and others, his campaign advisers understand that issues of campaign finance do not rank high in most voters’ minds.

By releasing his first ad of the general election, Obama also diluted the impact of the money story with a strong visual that was likely to dominate the day’s television coverage of the campaign. Obama will draw attention to his finances again on Friday, when his campaign files its May fundraising report with the Federal Election Commission.

His decision represents a significant milestone in the financing of presidential campaigns. President Bush was the first candidate to reject public financing of primaries when he ran in 2000. But no candidate has ignored the general election funds since the law that created the system was approved in 1976.

“It’s not an easy decision, and especially because I support a robust system of public financing of elections,” Obama told supporters in a video message Thursday. “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 said Obama was breaking his word. “I strongly feel that Senator Obama ought to review his commitment not to me, but to the American people, which he has gone back on,” the Arizona senator said at a campaign appearance in St. Paul., Minn.

McCain, long a proponent of tougher campaign finance laws, had committed to taking the public funds if his Democratic opponent did, too. By keeping his promise, he gets another issue to use against Obama.