We’ll see what happens tonight, but the Santorum scenario is increasingly based on winning the nomination at a convention rather than outright. The thinking is that if Romney is short of 1,144, he’ll be at his strongest on the first ballot and recede thereafter. This is often the dynamic at conventions. Just ask William Seward. But, even if he’s short of 1,144, Romney will almost certainly have the most votes and the most delegates and therefore, as Jay Cost put it here, a moral claim on the nomination. To nominate someone else instead at that point — someone who receieved fewer votes, or perhaps didn’t run at all — would be an extraordinary thing. I’ve said this before, but if Romney is first but short of 1,144 and Santorum is a strong second, the most natural play would seem to be a Romney-Santorum ticket that rewards the first- and second-place finishers who happen to complement one another very well demographically, and geographically, at least on paper (the actual workings of this ticket would be something else altogether).