As he goes into the second debate, John McCain is more than ever the unhappy warrior of the 2008 campaign. His grumpy hostility toward Barack Obama in their first face-to-face encounter—face-to-face for Obama, that is—reflects feelings he can barely disguise. The day after Sarah Palin caricatured herself in the vice presidential debate, McCain lashed out at “my old friend Biden,” his words uttered through a manic smile stretched taut across his teeth. It was a smile of malice, like Jack Nicholson’s in “The Shining.”

A McCain aide has told friends that what kept the campaign going in the primaries was their hatred of Romney—and what keeps them going now is hatred for Obama. As McCain’s polls crater, nationally and in the battleground states, this enmity is fired by the rising prospect of defeat. Although they won’t say it publicly, more and more Republicans are convinced they will never see or say “President McCain." A Reagan-Bush grandee, one of the smartest strategists in the GOP, observed after the first debate that Obama had had his Reagan moment: onstage with his rival, he’d crossed the threshold as a credible President, much as Reagan had in 1980. In the view of this Republican wise man, the election is all but over.

Jimmy Carter only had six days to campaign after that fateful debate; McCain has four weeks. His handlers have announced, in effect, that he will run the rest of the race as Mr. Nasty, trying to claw his way back by ripping at Obama.

I doubt McCain could rein in his scorn in the two remaining debates eve if he wanted to. In my career as a political consultant, I’ve advised candidates who, under pressure from impending defeat or in the grip of an implacable animosity toward their opponent, just couldn’t help revealing their true feelings—no matter what they were told. Voters recognize disdain and react against it, as they did watching McCain at Ole Miss.

His mean style will be complemented by mean substance. In what could be the filthiest final weeks of a modern Presidential contest, McCain will not be content with repeating the falsehood that Obama is a “liberal” who will raise “your taxes.” No, the final tact from a purely tactical campaign will be personal and ugly.

We’re seeing a preview now in the empty-headed Palin’s claim that Obama is “palling around with terrorists.” In lieu of a plan to revive the economy or reform healthcare, McCain offers smears. There’s a racial subtext, too, as there has been from the start of the attacks on Obama as “elite” and a “celebrity.” (Read: “uppity.”) Listen to Palin: “This is not a man who sees America as you see America and I see America.”

Frum doesn’t like that argument. But I am more convinced today than when I first wrote it that the election will be a test of America’s character. Also of “thoughtful” conservatives like David Brooks—will he rationalize the smears?—and George Will. (If it was wrong for McCain to traduce SEC Chairman Chris Cox, a friend of Will’s, isn’t it equally wrong to lie about Obama?)

McCain’s low road is also a test for the Democratic nominee, his last test before the presidency. The McCain forces may hope to make Obama angry, so he loses the sense of calm and reason that has provided so striking a contrast with the erratic and impulsive McCain. Or they might have hoped Obama would studiously stay above the battle. He won’t do either. Instead, he’ll answer the lies and tie the tactics to the emptiness of McCain’s campaign and his betrayal of his own character: he doesn't have "answers"; just "attacks."

The hollowed-out McCain, who put country last in giving us a vice-presidential nominee who’s a refugee from a Christopher Buckley farce, now sinks lower. But facing two wars and an economic crisis, I believe America will not sell its future and its soul for 30 pieces of mud. Let McCain leave his honor in the dust of the low road. The American people, I predict, will keep theirs—and prove again that the unhappy warrior does not prevail.