If he had accepted the $84 million in public funds, the Illinois senator's campaign would have been limited to spending that amount for all expenses from the end of the Democratic National Convention at the end of August through the November election.
By forgoing the money, the Obama campaign instead can spend as much as it can raise. The campaign has demonstrated vast fundraising prowess in the Democratic primaries. The campaign now could spend $100 million or more on advertising alone.
The extra money could allow the campaign to target more states with advertising and also to do a national ad overlay to its state-by-state advertising. No presidential candidate in recent years has used national network TV advertising, though four years ago there was some use of national cable.
The Republican National Committee was quick to hit Mr. Obama for breaking a previous pledge to use public funding. RNC Chairman Robert M. Duncan said in a statement: "In his decision to break his promise and forgo our nation's public financing system, Barack Obama failed to demonstrate the kind of principled leadership that Americans are looking for in our next President. Obama's decision is what we've come to expect from a candidate whose rhetoric is nothing like his record, and it undermines his own claims to represent a 'new' kind of politics. Clearly, Barack Obama is just another politician who is willing to do whatever benefits his own personal agenda."
Mr. Obama in a statement posted on the campaign's website said the decision wasn't an easy one, but said it was necessary in light of a "broken" campaign financing system.
"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," he said. "John McCain's campaign and the Republican National Committee are fueled by contributions from Washington lobbyists and special interest PACs. And we've already seen that he's not going to stop the smears and attacks from his allies running so-called 527 groups, who will spend millions and millions of dollars in unlimited donations."