Mitt Romney appeared to regain his footing this weekend. After being swept by Rick Santorum in the Missouri primary and in the Minnesota and Colorado caucuses, Romney rebounded with victories in the CPAC straw poll and the week-long Maine caucus.

But Romney could soon face his toughest battle yet, and in the place he would have least expected it: Michigan. Rick Santorum is winning over Republicans and blue collar Reagan Democrats in the Wolverine State and has scratched his way to the top of the polls. The American Research Group currently has Santorum leading Romney by six points (33 percent to 27 percent). Meanwhile, Public Policy Polling gives Santorum an even more substantial lead of fifteen points (39 percent to 24 percent) and notes that he is ahead in every area of the state except Oakland County, where Romney grew up. This is not good news for Romney.

Should Romney lose to Santorum in Michigan, be it by six points or fifteen, it will be a stinging rebuke. After all, the people of Michigan thrice elected his father George Romney during the 1960s, though one could argue that the elder Romney is a distant memory now. That said, the younger Romney convincingly won the state’s 2008 primary, beating eventual GOP nominee John McCain by nine points. A loss in Michigan on Feb. 28 could very well put a dagger through the heart of Romney’s campaign, even if he were to win the Arizona primary later that same evening. If Romney can’t beat Rick Santorum in Michigan, then how could he expect beat President Obama there?

However, Romney has time on his side. Two weeks to be exact. If a week in politics is a lifetime, then two weeks is an eternity. It is more than enough time for Romney to sharpen his Wolverine claws and rip Santorum to shreds, as he did with Newt Gingrich last month in Florida following the former Speaker’s upset victory in the South Carolina primary.

The question now is whether Santorum’s hide is thick enough to withstand Romney’s persistent attacks. I’m not sure how helpful it is for Santorum to suggest that Romney rigged the results of the CPAC straw poll. This is something on which Santorum ought not dwell. He is far better served by looking ahead than by looking back. As Satchel Paige often said, “Don’t look back. Something might be gaining on you.” In this case, that something would be Romney with his teeth bared. Given what is at stake on Feb. 28, these encouraging poll numbers for Santorum in Michigan are certainly more worthy of his attention than a far less consequential straw poll.

Besides, what exactly can Romney say against Santorum? He cannot credibly criticize Santorum on social issues, such as abortion and gay marriage, without drawing attention to his own inconsistencies on those matters. He certainly cannot criticize Santorum on foreign affairs and national defense. At best, Romney can call Santorum a Washington insider and accuse him of pork barrel spending and earmarks. But whatever Santorum’s transgressions from his days on Capitol Hill, they pale in comparison to Romneycare, which hangs over the former Massachusetts governor’s perfectly coiffed hair like the sword of Damocles. It certainly doesn’t help Romney that Santorum has been more effective than any other Republican rival at drawing attention to its shortcomings, so much so that Romney referred to his own scheme as “Romneycare” in one of the recent GOP debates.

Another factor working against Romney is that many conservatives do not want him to attack Santorum in the manner he did Gingrich. As Byron York noted in the Washington Examiner, a group of conservative activists met with Romney prior to his CPAC speech and beseeched him to refrain from going after Santorum. Clearly, Santorum has not made enemies on the right the way Gingrich has, and while many conservatives were more than happy that Romney went medieval on Gingrich, the same cannot be said when it comes to Santorum. Romney could pay the price for disregarding this counsel.

The only way Romney’s strategy will work is if Santorum, like Gingrich, becomes his own worst enemy. If Romney can manage to get Santorum to sound like a sullen, sanctimonious, scolding sourpuss in the next two weeks, then he will have found a way to turn back yet another Republican challenger. But if Santorum’s skin proves thick enough, Republicans might very well defang Romney.