The only real impact of the former senator deserting Romney is a flurry of national media attention. Inside Ohio, voters are likely to shrug.

If you're convinced that the sky is falling on Mitt Romney, Mike DeWine's endorsement of Rick Santorum today is certainly evidence for your point of view. The Ohio attorney general -- who was a U.S. senator from 1995 to 2007 -- made the surprise announcement Friday afternoon that he's switching his backing from Romney to the former Pennsylvania senator. The former Massachusetts governor, who's also the former "inevitable" nominee, has recently lost three primary contests, narrowly won the Maine caucuses, and is now sputtering out in Michigan, his native state. As if that wasn't bad enough, a backer in a key Super Tuesday state has now abandoned him.

You probably shouldn't buy that line of thinking, though. Here's why the DeWine endorsement doesn't matter.