Jonathan Bernstein thinks last night’s results were important for Santorum’s political future:

Rick Santorum isn’t just going to mathematically finish second in votes and delegates; he’s going to be perceived as having been the clear runner-up. He’s going to be 2012’s John McCain 2000, Bob Dole 1988, George H.W. Bush 1980.

That’s worth something. It may well be worth the VP nomination, as it was for Bush (and for John Edwards in 2004). We’ve always known that Mitt Romney, like John McCain, would need to pick a running mate who would please social conservatives and others who were unenthusiastic about him. It now appears that Santorum will, if he survives the vetting he’ll be getting over the next weeks, become the front-runner for that slot. If he gets it, then win or lose, he’ll have an excellent chance of winning a future presidential nomination.

I’m not sure what changed in the last week, but Santorum as “next in line” makes no more sense now than it did before he won Alabama and Mississippi. As I said a few days ago, selecting Santorum as the VP nominee may help Romney in some ways, but there are others that could help him in similar ways without having Santorum’s liabilities. If the party really were fractured along factional lines, picking Santorum might be necessary to unify Republicans. The party isn’t fractured, and a unity ticket isn’t necessary. If Romney selected Santorum, that would give Santorum a head start over future Republican competition, but it wouldn’t take him anywhere unless he and Romney won. Losing VP candidates rarely win their party’s nomination later on. It can happen, but two of the last five losing VP nominees didn’t even try and the other three were unsuccessful in their attempts.

It isn’t Bernstein’s concern in his post, but selecting Santorum as the VP nominee would be a bad idea. It would be a drag on the Republican ticket. If the first rule of selecting a running mate is to do no harm, Santorum shouldn’t even be on the list of candidates. It depends on the specific groups of voters we’re talking about, but Santorum has the distinction of being radioactive to several groups of voters at the same time. Selecting him would tell voters with even mildly libertarian views that the GOP ticket has nothing to offer them, and voters weary of foreign wars and entanglements would be confronted with the prospect of electing a new Cheney. Romney’s favorability with independents is already quite low, and selecting Santorum isn’t going to make it any easier to improve those numbers. Having Santorum as Romney’s running mate would be a daily reminder to the public of almost everything they came to dislike about the Bush administration, which is exactly what Romney needs to avoid doing in order to win.