It is fair to say John McCain has stumbled since the triumphant Republican National Convention. In the course of a week, he went from inspiring doyen to tactical opportunist. He introduced the world to Sarah Palin, the most exciting thing to hit the GOP since Ronald Reagan; he made a speech in praise of bipartisanship and American unity in the face of history’s challenges.

Then he moved effortlessly to Swinegate and kindergarten sex-ed. Forget the merits of the charges; the tone was problematic. After announcing that Americans don’t hide from history, they make history, John McCain made hay. He took schoolyard potshots at his opponent. That undermined the seriousness of his pledge and tilted an electorate still trying to figure out just what they thought of this intriguing new ticket. As went McCain’s tone, so went his poll numbers.

During the GOP Convention, McCain had guided the election into its most elevated phase, and the advent of Sarah Palin rescued McCain’s pledge of old-fashioned decency from sounding like sheer nostalgia. After the GOP Convention bounce, Obama was disoriented. He had nothing to work with. More than that, he was exposed. He wasn’t the fresh-faced outsider; he wasn’t the voice of change or the catalyst for unity. In fact, while his rabid supporters sullied themselves digging for non-existent scandal in Alaska, the Obama phenomenon began to look depraved. It was time for McCain to sit back a bit. He found a theme in American courage and his VP gamble paid off in a brilliant package. He was triumphing both as American hero and as maverick. Having claimed the high road, he should have taken it. Instead, he gave the Obama camp material in the form of manufactured outrage and an inflammatory charge–lifted from an Alan Keyes campaign, no less.

During a September 11 forum on national service, McCain said, “I think the tone of this whole campaign would have been very different if Senator Obama had accepted my request for us to appear in town hall meetings all across America. . .” That’s the unmistakable language of punishment.

But who does McCain think he’s punishing? And to what end? Trashy politics isn’t some old reliable weapon that will do the job if you just have the nerve to bring it out. It’s a risk, because it’s an insult to the electorate. It’s also not an organic feature of John McCain’s persona. And for that reason, above all others, he should cut it out. McCain went from leader back down to underdog in no time. He won’t be able to reclaim the upperhand quite that fast, but he’ll never get there again if he doesn’t set his campaign clock back to the morning after his Minnesota high point.