How is Carter's attack criticism "personal"?

I get that the wingnuts are freaking out because Jimmy Carter said such mean things about the Bush Administration, and just how awful that is, blah, blah, blah. But I noticed that the White House immediately called his comments a "personal attack," which struck me as very odd. And now so is Mike Huckabee.

"President Carter violated an unspoken code that you don't make personal attacks on others who currently hold the job -- you just don't," he added.

Here is what Carter said:

“I think as far as the adverse impact on the nation around the world, this administration has been the worst in history.”

Not a personal attack. An attack, certainly. But there's absolutely nothing personal about it.

Such fragile flowers.