Fun, fun, fun via David Brody, not because this is remotely likely to happen — how would RS explain away calling Romney the worst Republican in America to run against Obama on health care? — but because Santorum knows it isn’t and knows the answer he has to give regardless. His weariness at this endless campaign-trail nonsense is palpable. I’m trying to imagine any circumstance in which Romney passes on Rubio and Paul Ryan and Christie and Jindal and Daniels and Bob McDonnell and Susana Martinez and Nikki Haley to choose a guy who (a) lost his swing-state Senate seat by nearly 20 points, (b) has spent weeks hammering the message that Romney’s waaaay too much like Barack Obama where it counts, and (c) is guaranteed to get the campaign sidetracked on “values” issues while Romney desperately tries to stay on his economic narrative. The only scenario I can think of is if Santorum holds Romney to a plurality of delegates by the time the primaries end such that the only way he can reach a majority is if he gives Santorum whatever he wants. But don’t forget, in the end Romney will pad his total with lots of superdelegates, plenty of Ron Paul delegates when their deal is eventually made, and some Gingrich delegates who peel off at the end of the first convention ballot. That is to say, for Santorum to elbow his way onto the ticket, he’d have to hold Romney to a relatively small plurality of delegates, not a near-majority. And since Romney seems to be building momentum now just as the winner-take-all states start voting, that seems unlikely.

Pennsylvania votes on April 24. Santorum will probably hold on, but a huge money advantage plus some heavily populated urban areas plus an increasing sense of inevitability equals a potential Romney upset. If he beats Team Sweater Vest on its home turf, I assume the campaign ends that night. Exit question: If Romney/Santorum doesn’t do it for you, how about … Romney/Gingrich?