For some time now, I've been suggesting that one of the possible reasons that Bush maintains some degree of support is due to the sheer ego of those supporting him.
They've not only invested their vote, their lone political voice in the process, but in defending this man and his policies, they've also put their own egos, their own reputations on the line. They've made firm, loud proclamations of what a "great leader" Bush is, even in the face of grand fiascos, foreign and domestic.
I don't think these folks are intellectually incapable of seeing the folly of their position. Instead, I think that their egos are fully and totally in control and will simply not allow them to admit they were wrong in their assessments.
Now, the tendency isn't so implicitly horrible, and it's certainly not limited to conservatives. It's a fundamental human trait, for better or worse, and we're all prone. Go ahead and try and tell Mommy that her 65 pound three-year-old is overweight and be prepared to hear a dissertation on what it means to be "big boned".
However, there comes a point in any responsible person's life at which they recognize the disconnect between their fealty and their reality, and if they've any sense of ethics at all, concessions are made in favor of what's plainly been established.
And herein lies the problem, as I see it. Bush's loyal fans have shown themselves to be plainly irresponsible. They don't care that his failures are nearly beyond counting. They don't care that he's surrounded himself with nefarious sycophants and abdicated the power of his role to some of the most greedy, corrupt and calloused human beings to ever sit in Washington.
Why such apathy? Because they steadfastly refuse to acknowledge the grievous mistake of voting for GW, for sending a GOP majority to Congress, and for enabling the virtual destruction of American democracy as we know it.
Marc in KS picks up this headspace and helps explain it using an economist's frame, in discussing the "sunk-cost effect". Check it out.