When you look at it, the enthusiasm for Santorum isn't great enough, his statements have been too divisive, and as much as Republicans don't love Romney, they want to see if they can win.
Honestly, I don't fully understand the extent of Republican rage when it comes to Obama. If anything, I think one could argue he has fallen short of being the true liberal so many on the left were hoping to see. He has pandered to financial interests, stayed soft on speaking out against atrocities like Gitmo, and signed the controversial new defense bill with questionable constitutionality.
He gave Republicans the tax cuts they wanted, the continuation of aggressive totalitarian style security, and passed a healthcare plan that will give unimaginable amounts of money to already wealthy insurance companies. His healthcare plan is basically Mitt Romney's!
Anyway, for some reason they can't stand him. He seems too foreign, too internationally minded. There's that picture of him holding Fareed Zakaria's unfortunately titled book "The Post-American World" - I think Fareed wanted a title that would provoke, but in the end he's had to stretch to explain what he means over and over again. In the end was it really worth titling it that?
Anyway, that aside... Republicans want to win this election and unless I saw their enthusiasm at incredible levels for Santorum, I think they'll stick to their initial gut and go with the guy they think disenfranchised Democrats might just show up to the polls to support... Or just not be so terrified of that they'll not show up to the polls.
You see Santorum may get more of the base, but the base is already so enraged at Obama they'll vote for anything - a box. Or in the case of Romney, a robot. But without that enormous enthusiasm behind Santorum, even if he seems more "authentically conservative" to them, I just don't see him winning the nomination. There is a significant portion of very strategic Republicans and they see a window for victory, and that window is the disenfranchised Democrats.
I still think Obama will win in 2012 against Romney. I don't believe the Republicans have anything better to offer, only a return to the vicious Bush policies that got us into some many of the problems we are presently dealing with. People will argue that McCain lost because of Bush, and that Obama can't play that card again, but I think he can. Why not? Unless the party has really changed its policies, and they haven't, despite this supposed Tea Party revolution. Exactly the same party. One message. One thing. No taxes. Less regulation. Make abortion illegal. Don't let gays marry. I don't see them bringing new ideas to the table.
Younger voters are seeing Republicans as more and more out of touch. We're a generation of people who do want to allows gays to marry and enjoy the same rights as the rest of us, we don't see smaller government as the solution in a society where we're competing against countries with universal healthcare, and we enjoy civil liberties and freedoms and don't want to give them away just for a false sense of security. We're not fond of rushing into wars we don't need.
All that taken into account I don't think any Republican can win in 2012, but Romney does stand a better chance than Santorum.