Santorum is not only the clear alternative to Romney, he is the only alternative to Romney. Gingrich has a virtually impossible shot at clinching the nomination (see below link) besides the sobering fact that in a diverse state like FL (a key battleground state that Obama carried in 2008), he lost among all major demographics and suffered a massive 20-point deficit among female workers. And Santorum is telegenic, has mid-western roots, is Catholic, and could haul in Reagan Democrats. Besides, as favorite son, he will carry PA.
Perhaps that's what McRombama is thinking...with Rick as his VP pick.