But Mr. Rove understood that the facts were irrelevant. For one thing, he knew he could count on the administration's supporters to obediently accept a changing story line. Read the before-and-after columns by pro-administration pundits about Iraq: before the war they castigated the C.I.A. for understating the threat posed by Saddam's W.M.D.; after the war they castigated the C.I.A. for exaggerating the very same threat.

Mr. Rove also understands, better than anyone else in American politics, the power of smear tactics. Attacks on someone who contradicts the official line don't have to be true, or even plausible, to undermine that person's effectiveness. All they have to do is get a lot of media play, and they'll create the sense that there must be something wrong with the guy.

And now we know just how far he was willing to go with these smear tactics: as part of the effort to discredit Joseph Wilson IV, Mr. Rove leaked the fact that Mr. Wilson's wife worked for the C.I.A. I don't know whether Mr. Rove can be convicted of a crime, but there's no question that he damaged national security for partisan advantage. If a Democrat had done that, Republicans would call it treason.

But what we're getting, instead, is yet another impressive demonstration that these days, truth is political. One after another, prominent Republicans and conservative pundits have declared their allegiance to the party line. They haven't just gone along with the diversionary tactics, like the irrelevant questions about whether Mr. Rove used Valerie Wilson's name in identifying her (Robert Novak later identified her by her maiden name, Valerie Plame), or the false, easily refuted claim that Mr. Wilson lied about who sent him to Niger. They're now a chorus, praising Mr. Rove as a patriotic whistle-blower.