The biggest question I've had about McCain's new plane, the Straight Talk Express Lap Dog Express, is how he could afford it.

I know he's got the cash to pay for it now -- he actually outraised Barack Obama in both April and May (we don't know about June yet) -- but the problem is that unless he plans to abandon the plane before the convention, he's actually going to need to allocate the costs for its renovation to his general election campaign fund, which is theoretically limited to $84 million.

(In truth, the RNC can spend unlimited sums on his behalf, so this limitation is mostly meaningless if he breaks his promise to limit himself to public financing.)

John Kerry faced this problem in 2004. Last May, the FEC ordered the Kerry campaign to repay $1.3 million to the U.S. treasury for having exceeded spending limits imposed by the presidential public financing system, a decision which is currently under appeal.

FEC auditors found the campaign spent nearly $1.4 million more than federal rules allowed, primarily on customizing two planes and on payments to its media firm. ... The repayment includes more than $500,000 in labor costs associated with reconfiguring the Boeing 757 that jetted Kerry around the country and the Boeing 727 that carried Edwards. But those expenses could be the subject of a tussle between commissioners if the appeal by the Kerry-Edwards campaign results in an administrative hearing, as expected.

The campaign had sought to bill those labor costs to Kerry’s primary campaign committee, but the auditors invoked accounting rules known as Generally Accepted Accounting Principles, or GAAP, to argue the labor costs should be considered part of the cost of the planes – and thus should be charged to the general election campaign.

Weintraub and FEC Chairman Robert Lenhard, both Democrats, expressed a willingness to reconsider the labor costs, while two Republican commissioners seemed to agree with auditors.

From everything that I've learned about the new Lap Dog Express, it seems likely the costs will outstrip those incurred by the Kerry campaign.

In the end, I suspect that what will actually happen is that McCain will do whatever he darn well pleases -- even if he knows it's not in keeping with the rules -- and he'll beg for forgiveness later.

After all, it's okay if you're a Republican.