I am not certain the GOP leadership or its backers are treating the Presidency as a serious goal in this election. Sure, they'd probably like to have it, but if they are actually as amorally rapacious as we generally believe them to be then they may well have decided to make the best of a weak position in this election. That best would be focusing on holding on to their own personal power as long as possible while discrediting the Democrats' agenda, because that agenda would inevitably result in their removal from power if it succeeded. They would either get voted out, become politically marginalized, or end up paying their fair share in taxes.
Congressional Republicans are already doing all they can to block forward progress on the economy and every other front, while Republican opinion leaders blame the President for the fact that so little progress has been made. They'd be in a far better position to keep that up if Republicans controlled both houses of Congress.
As it is now, the Republicans still have an excellent chance of retaining control of the House of Representatives. We'll have to lose no safe or leaning Dem seats and pick up a LOT of their seats, including many leaning their way, in order to take it back. No, it is absolutely not impossible for us to do that, but our chances aren't stupendous, either (although even if we don't make it, any progress towards Speaker Pelosi would be good, especially as we could build on it in two years). Meanwhile, the Republican's chance of picking up the Senate either in this election or the 2014 midterms is not minuscule. Intrade currently (as of writing this) gives them a 53.3% shot at taking the Senate in this election, although I personally believe that is too high and plan to plunk some money down on a bet against it.
They had no poisonously charismatic Reagan clone to run this cycle, so it probably didn't much matter who won the elephant races. The odds were always against any of their candidates managing to unseat our relatively well-liked (by most of the country) President. But, of course, they'd have to run somebody. I think a fair number of GOP voters would turn out to vote against President Barack Obama who would not turn out to vote for the downticket races alone. Not this year, anyway. They need those negative voters. So they've got to have someone. Anyone, really.
Wouldn't it explain so much if the GOP leadership saw Romney as just a dupe, a placeholder, an "anyone, really" candidate there to encourage GOP voters to come to the polls, to give them the illusion they actually had a chance to turf out Barack Obama? I mean, if the GOP leadership does not care about the country or about policy (and so far as I can tell, they don't), then they don't need to worry about the difficult problems we face or the impossible task of making the Republican Party look good. Not when it is so much simpler to just keep the Democrats from getting any success or any credit.
I dunno. It's all conjecture. But is it likely or unlikely conjecture? And does it matter either way?