Actually, I think the biggest thing that brought about the Santorum collapse was calling President Obama a snob. I know an awful lot of moderate voters who heard that and pretty much just crossed Santorum off their list of people they might end up voting for in March or in November.
I think it was more about resurrecting all those speeches Rick gave to Catholic audiences about the toxic societal effects of higher education and contraception as an anti-life concept and the disengagement of mainline Protestant churches from the Judeo-Christian ethic, given before he decided to run for President, which Rick then doubled down on. Rick if you are going to give these speeches, keep the darn cameras away is my best advice.
Interestingly in my experience, none of my friends (ranging from Atheists to mainline Protestants to Catholics; not many Evangelicals though
) has seemed to care much about that, but the "snob" comment for some reason started an uproar. Perhaps it's just that my friends are mostly very educated people who are somewhat politically indifferent.