John McCain has got nothing left in his tank except toxic fumes.

But he’s going to be spewing those out in these last four weeks.

Already, his campaign has indicated, through surrogates and friendly mouthpieces in the media, that he’s going negative.

Sarah Palin didn’t waste any time this weekend, saying Obama had been palling around with terrorists. And, after some encouragement from William Kristol, she suggested that the McCain campaign should make an issue out of the Reverend Jeremiah Wright.

Even though McCain eschewed that tactic early on, I wouldn’t be at all surprised to see it in his ads—or even more so in those by Swift Boat-style groups. Hell, we may even see Obama in Muslim garb, again. And Michelle sounding militant.

McCain’s aides want to move the topic away from the economy, and who wouldn’t in their shoes?

The Bush economy, which McCain supported not only philosophically but in vote after vote, has gone off a cliff, and it’s pulling McCain down with it.

But if McCain goes mean himself in the debate, he may lose more than he gains.

Many people don’t like direct personal attacks, and he came off too caustic in the first debate, especially with women.

Even an occasionally reasonable Republican, like Peggy Noonan, suggested on Meet the Press on Sunday that she would be turned off by the nasty approach, and that it would be bad for the country.

Yet McCain knows he can’t win on the high road.

So buckle your seat belts for a bumpy ride on the low road, a road that’s putting country last.