The presidency is too-large-for-life because the president is the head of a government that is simply too large. (The too-large-for-life factor also reportedly is why Indiana Gov. Mitch Daniels, who I’d place well above Barbour on my list, has been on the fence about running.)

Not to excuse bad decisions by any president, but I have to wonder who, exactly, could perform the job as it stands today, evolved and mutated in so many ways. And let’s not overlook that President Obama and his immediate predecessor, George W. Bush, didn’t help matters with their efforts to expand the federal government and the president’s role in it.

In fact, I think the too-large-for-life presidency also reinforces the polarization of politics — which in turn further explains the “all-consuming effort,” in Barbour’s words, it takes to become and serve as president. A president invariably will disappoint or even anger his base with some of his actions. But, because he is responsible for so much, his supporters are often hesitant to object too strenuously, lest it weaken his ability to act on other policies on which he and they agree.