John McCain has made great strides since his campaign was written off a few months back. He has been a presence in the debates, he continues to outpoll Mitt Romney nationally, and he has kept himself in the mix. But there’s one reason I’ve never taken the McCain comeback theories as far as others: money.

Marc Ambinder has parsed the FEC data. The McCain campaign effectively has no money, owing rent, a past due American Express bill, and other debts totaling $94,000, even after you factor in the $1.8 million they raised toward the general election. And contrary to initial reports, it appears that Ron Paul actually did outraise McCain for the primary in Q3.

Worse, if the campaign accepts public funding they might hit the spending caps: they’ve already spent $288,000 toward Iowa’s limit, $234,000 toward New Hampshire’s, and $230,000 toward South Carolina’s. That means McCain could only spend $584,000 in the must-win state of New Hampshire.

McCain could have a suprise is in store for us, but these numbers place serious constraints on his bid for the Republican presidential nomination.