A short time ago, I asked David Wasserman of the Cook Political Report about the GOP candidates’ prospects in Michigan. In 2008, Mitt Romney won by nine points, but lost the more conservative, western area of the state. Wasserman told me, “that area will just be difficult for him” this time around. It’s no so much an ideological issue, he said. “The bottom line on Romney vs. Rick Santorum/Newt Gingrich is this divide between upscale R’s and downscale R’s.”

He explained it comes down to the difference that some pundits have characterized as Cracker Barrel vs. Whole Foods. “Take Colorado last night. Santorum won all four counties with a Cracker Barrel, while Romney won five of six counties with a Whole Foods. It’s Cracker Barrel vs. Whole Foods Republicans.” The problem for Romney is that among Republicans “that Whole Foods Republicans have been on the wane in the past few decades while Cracker Barrel Republicans have become a bigger and bigger bloc.”

I took a quick look at Michigan. There are seven Whole Foods and sixteen Cracker Barrels (although there may be multiple stores in a single county). If Wasserman is right, and this comes down to a socio-economic split, then Santorum might have smartly picked Michigan rather than Arizona (where the Cracker Barrel to Whole Foods ratio is 13:7).

No wonder Romney was talking about his rags-to-riches father last night. Expect more of that, and an economic pitch aimed straight at those middle class voters.