1. We have caucuses here, not primaries. You don't just stop by the caucus on your way home from work; you spend an entire evening sitting somewhere like a middle school classroom, following the Robert's Rules of Order and listening to people propose "resolutions" (which, if you're a Democrat, may eventually get incorporated into your party platform. This does not stop people from proposing huge numbers of resolutions for things that are ALREADY in the party platform. I'm actually not sure whether Republicans participate in this particular ritual, or not.)
2. In addition to the time commitment, you have to be an honest-to-God party member to go to a caucus. Joining the party is quite straightforward: you sign in at the door. However, they are fairly serious about not wanting you there if you do not honestly consider yourself aligned with the views of that party. Given that you caucus with your precinct -- which is to say, with your neighbors -- you could actually be challenged and evicted if your neighbor points out that you still have a Wellstone sign in your yard and a bumper sticker that says "Friends Don't Let Friends Vote Republican." (It's unlikely, because Minnesotans aren't very confrontational, but it could happen.)
3. Also, when you sign in they want your phone number and they will call you FOREVER. And so will all the candidates. And the national party fundraisers. And so on.
4. So it's only the really MOTIVATED people who go to these. And historically, the really MOTIVATED Minnesotan Republicans have been hair-raisingly conservative. HOW conservative, you might be wondering?
5. Back in the 1990s, we had a wildly popular Republican governor, Arne Carlson. The state Republicans declined to endorse him, instead endorsing Allen Quist. (Who was then utterly humiliated in the primary, illustrating the overlap between "Minnesotans who go to caucuses" and "Minnesotans who vote.")
6. Caucusing Minnesotan Republicans went for Romney in 2008. But that was before Obama took Romney's health care plan to the national stage and the Republicans decided they hated it. Also, he was the underdog at this point in 2008, and Minnesotan Republicans were convinced that McCain was a liberal in Republican clothing, much like they're convinced of that this year with Romney.
7. Ron Paul tries to pull in Independents, but the whole caucus setup is not very independent-friendly. I'm surprised he did as well as he did.
8. There's no way Minnesotans were going to go for a meanie like Newt. Santorum is a dickhead, but he's a mild-mannered, personable dickhead. The sort of dickhead a Minnesotan can feel comfortable with. Newt, not so much.
So: yes. Santorum surges in Minnesota. This isn't because Minnesota is a particularly conservative state, but because we run caucuses. In the highly unlikely event that Santorum wins the Republican nomination, he'll be trounced in Minnesota.