On Monday morning, the eve of caucuses and primaries in Minnesota, Colorado and Missouri, the Romney campaign sent out notice it would hold a conference call to discuss rival Rick Santorum’s “long history of pork-barrel spending.” The call would feature former Minnesota Gov. Tim Pawlenty explaining why Santorum “is simply not ready to be president.”

Santorum’s aides were delighted to hear the news. “They’ve turned their attack machine against us in the last 24 hours,” top adviser John Brabender said that afternoon. “I can only read into that that they’re looking at polling numbers telling them we’re their biggest threat. It’s a badge of honor that Romney has decided to try to destroy us.”