Back in 1990, after a series of disturbing crimes, the New York Post chastised David Dinkins, New York's soft-spoken, liberal, Democratic mayor, with a front-page headline that would haunt him for the rest of his single term in office: DAVE, DO SOMETHING.

In a rational world, similar headlines would be haunting George W. Bush -- especially this week.

But it isn't happening, and it won't. There's a simple reason for that: Most Americans believe the common stereotypes of liberals, conservatives, Democrats, and Republicans, and most Americans simply can't reconcile those stereotypes with contradictory facts.

If a war under a Democratic president were going as badly as this one is going under Bush, it would play into every stereotype of Democrats and liberals: anti-military, uncertain whether they really want America to triumph, peace-loving, timid. If, day after day after day, years after the war seemed to be won, American troops were dying in ever more horrible attacks and a Democratic president seemed to have absolutely no idea of how to stop the bleeding, it's easy to imagine the imploring headline: AL, DO SOMETHING or JOHN, DO SOMETHING.

But the stereotype of conservative Republicans is that they're tough, aggressive, patriotic, and pro-military -- and most Americans believe that George W. Bush is the living embodiment of that stereotype. A Democrat who gets to the White House is invariably accused of weakening the military and bringing shame to America in the eyes of the world; George W. Bush is actually doing those things, yet Americans can't grasp that -- the conflict between the GOP stereotype and empirical reality creates a cognitive dissonance. How can that man in the flight suit be making us weak? How can that man who loves making speeches to the troops, like the one on the deck of the Abraham Lincoln, be decimating the military?

It's possible to rewrite stereotypes, but it takes years and a disciplined message machine. Facts aren't necessarily relevant -- the GOP is now able to call itself the party of ordinary people (and the Democratic Party the party of elites) even as a son and grandson and great-grandson of wealth sits in the White House and aggrandizes the rich. But there's no evidence right now that the Democrats have the ability to poke holes in America's political stereotypes -- or even realize that that's what they have to do.

Meanwhile, a war goes badly, and yet the public will never be as angry as it would be under a Democrat, which means there'll never be the public clamor for a change in course that there'd be if the president weren't Republican. (Yes, Bush's approval ratings are under 50%, but if he were a Democrat they'd be much lower.) The entrenched party stereotypes, in other words, are literally killing the troops -- and I'm afraid they'll be doing so for some time to come.