Sen. John McCain, R-Ariz. has officially broken the limits imposed by the presidential public financing system, according to reports filed last week by the campaign.

McCain has spent $58.4 million on his primary effort. Those who have committed to public financing can spend no more than $54 million on their primary bid.

So has McCain broken the law? The answer is far from simple, depending on whether he has withdrawn from the public matching program.

McCain's lawyers argue that the spending cap no longer applies. The Arizona senator was certified to enter the program last year when he was starved for cash. But once he started to win, he decided to hold off. On Feb. 6, after his Super Tuesday victories, he wrote to the FEC to announce he would withdraw. His lawyers said that gave him freedom to spend as much as he wanted.

But Federal Election Commission Chairman David Mason wrote McCain's campaign last month to alert him that the commission had not yet granted that withdrawal request, and that the commission would first need to vote on the matter. A snag: The FEC has four vacancies and therefore lacks a quorum to consider the matter.

Meanwhile, McCain's fund raising has roared ahead, now that he is the presumptive Republican nominee. McCain's campaign said Friday that it sees no ambiguity in the law.

"The FEC regulations specifically state that candidates who do not receive public funding payments from the U. S. Treasury are exempt from the primary spending ceiling," a senior McCain official said in an e-mail.