Forcing Mair out was like amputating your finger to deal with a paper cut. Instead of having a problem with a few Iowans and a writer at Breitbart.com, Walker has now baffled his admirers across the right. Mair’s resignation signaled that Walker’s team either didn’t do its homework before hiring Mair, or that it was too spineless to defend her. It is hard to believe the former, since Mair consulted for Walker before during his 2012 recall.

Walker’s unwillingness to defend his own hire will give other consultants and policy experts jitters before joining the team. It totally undercuts his reputation as a tough-minded fighter who stands on principle. And it may contribute to an alternate interpretation of Walker as a ‘fraidy cat. Earlier this month, Walker caved to Iowa ethanol interests by reversing his position on the federal mandate.

The problem, in other words, wasn’t the tweets of a single staffer, but the way Iowa’s parochial concerns act like kryptonite on Walker’s convictions and reputation. He can certainly recover from this, but if Walker thinks his path to the nomination runs through Iowa, he needs to figure out how to win that state’s caucuses without turning into Tom Vilsack before he arrives in Nashua, New Hampshire.