WASHINGTON — Campaign aides to John McCain said Tuesday that the Arizona senator didn't have to abide by public-funding limits between now and September. They said that Democrats making an issue of it were engaging in political gamesmanship.

The fight pivots on whether McCain, who applied for public financing after his campaign hit financial problems last fall, is obligated to stay within the system even though he never took any public money.

McCain said he could withdraw from the system simply by telling the Federal Election Commission that he was doing so; Democrats filed a complaint Monday saying that he can't withdraw without FEC approval.

The chairman of the FEC, David Mason, said in a Feb. 22 letter to McCain that the FEC must approve McCain's decision. Mason also wanted McCain to explain whether he'd used the potential public funds as collateral for a $4 million bank loan that his campaign received last fall; if he did, that would make it illegal for him to exit the system.

Trevor Potter, McCain's campaign lawyer, said Tuesday that the campaign never used its certificates for public funds as collateral for the loan. The campaign used all its assets — minus the public fund certificates — as well as "a commitment to raise money" as collateral, Potter said.

Besides, there's one big problem: For all intents and purposes, there is no FEC. There are four vacancies on the six-member commission. The Democratic-led Senate won't approve President Bush's nominees to the FEC. Without a quorum, the commission can't meet to take action.

"If there is no commission, the question becomes can a candidate be forced to remain within the system because the commission isn't there," Potter said Tuesday. "We don't object to the commission voting," he added. "We just don't think it's required as a matter of law."

The controversy could have two consequences for McCain:

• If he were forced to stay within FEC spending limits, he'd be severely limited in how much he could spend until he accepts the Republican presidential nomination at the party's convention in September. The FEC would limit McCain to spending $54 million in that period; he's already spent $49 million.

  Illinois Sen. Barack Obama or New York Sen. Hillary Clinton, who opted out of such limits for the primary season, can spend as much as they can raise until one of them accepts the Democratic nomination in August.

• Second, Democrats are using the situation to paint McCain as not the reformer he purports to be. That undercuts one of the core tenets of his campaign. In an election in which voters seem to want to change the way Washington works, it's important for a candidate to be seen as holding the moral high ground.

"John McCain's willingness to use matching funds when it helps his campaign and to break the law when it hurts him is exactly the sort of cynical politics and sheer hypocrisy the American people are already sick of," said Karen Finney, a Democratic Party spokeswoman. "John McCain should either obey the law by getting the FEC's approval to withdraw from the public-financing system they signed on to, or stop distorting the truth and admit that they're wrong."

"We're not dealing with a question of law or ethics," said Rick Davis, McCain's campaign manager. "We're dealing with a political issue. . . . We're happy to debate ethical standards and commitment to reform all day long."

To counter the Democrats, McCain is hitting Obama, the Democratic front-runner, for backing off a pledge that McCain says Obama made: that he'd accept public financing for the general election campaign if McCain did. That would limit each candidate to about $85 million for the period from the end of their conventions to the general election.

Obama says he didn't make that commitment. Said Obama spokeswoman Jen Psaki: "We're pleased that this option is on the table, and when Barack Obama is the nominee, we look forward to sitting down and discussing this with the Republican nominee. It would be presumptuous for us to make a decision beyond that before he is the nominee and before we have an opportunity to sit down with the Republican nominee."