To start with, wow.
As I wrote Monday, it was quite possible that Rick Santorum could have a big night. But nobody could have imagined quite how big.
In Missouri, Santorum blew Mitt Romney out of the water by 30 points -- garnering 55 percent of the vote and winning every county. In Minnesota, with 86 percent of precincts reporting, Santorum was winning with 45 percent of the vote -- and Romney fell behind Ron Paul, at just 17 percent support. But the real stunner was in Colorado -- where Romney lost to Santorum even though he comfortably led in polls and won there in 2008 with 60 percent of the vote.
How big of a deal is this?
On one side, it's pretty huge. The Santorum sweep will help him reemerge as the conservative alternative to Romney with voters still not sold on the front-runner. It shows that Romney remains vulnerable and pundits should rethink their assumptions that he's the inevitable nominee. True, when he won Colorado in 2008, it was as the conservative alternative to John McCain, so we can't full compare tonight's numbers to four years ago. But on the other hand, the mountain west was supposed to be a stronghold for Romney and given his money and organizational advantages, he should have coasted to victory. If he can lose in Colorado, he's theoretically beatable anywhere.
Also, it's worth noting that as Santorum was campaigning in these states, he attacked Romneycare harder than any opponent ever had during this race. In Missouri, in 2010, 71 percent of voters rejected the individual mandate in a ballot measure. The mandate, of course, was a central feature of Romneycare that Romney still defends as a state-level measure.
On the flip side, we shouldn't get too carried away. No delegates were awarded tonight, so all Santorum can get out of this is momentum. And as I pointed out earlier, momentum has proven fleeting in this primary season. Over time, Romney's money and organizational advantages should still make him victorious in a national primary, especially as Santorum now comes under more scrutiny -- and becomes the subject of Romney's negative ads.
All that said, the fact that Romney lost three states just when he should be benefiting from a "rally around the likely nominee" effect, and that turnout has been consistently low, points to a lack of enthusiasm for Romney that could haunt him in the general election even if he wins the nomination.