Finally, we are about to reach the last of those seemingly fateful moments that, it seemed, would never arrive in this seemingly endless campaign. Do you remember, say, mid-2007, when it was hard to imagine that the Iowa caucuses would ever actually take place? They felt then a lifetime away. But just like Christmas in Whoville after the Grinch had stolen the presents, somehow or other, they came just the same.

So the debates are upon us. The first comes on Sept 26, in Oxford, Mississippi, and is focused on foreign policy. By custom there won’t be as much campaigning as usual this week as the candidates hunker down and study their briefing books and rehearse their zingers. And rehearse they do, obsessively. They even have supporters “play” their opponent in mock-debate settings.

You may be familiar with some of the dramatic, history-turning moments. Gerry Ford saying in 1976 that there was no Soviet domination of Poland. Ronald Reagan asking voters in 1980 to devastating effect: “Are you better off than you were four years ago?” Bill Clinton locking eyes with a citizen in 1992 who asked him to put a human face on the deficit problem, as George HW Bush stood by mute. Al Gore sighing too much in 2000.

If that last example doesn’t seem of a piece with the others, there’s a reason. These days, debates aren’t 90 minutes. They’re 72 hours. In today’s American media culture of cable television and ideologically competing blogs, there is first the debate itself and then the debate over the debate. That spin starts during the debate itself. Both sides have teams watching the other guy and recording his misstatements and falsehoods. Emails are blasted to political journalists. By the end of the 90 minutes, the reporters may have 30 or 40 emails in their inboxes.

Then cable TV takes over. There’s an instantly declared winner, based on the pundits’ hunches and focus groups assembled by the networks. On the night of the debate, everyone may agree that Candidate A won. And that’s when the expert spin begins. Over the next three days, the side that was declared the loser starts spinning that the initial spin was wrong and they won. Sometimes, it works.

Hence Gore in 2000. It was generally agreed the night of the first Gore-Bush debate that Gore got the better of things. But in the succeeding days, the cable nets, led by the all but openly-pro-Republican Fox, started focusing on the question of Gore’s “condescending” sighs (when Bush lied about Gore’s tax plan, for instance). The sighs, shown repeatedly on cable, became the story, symbolic of the “fact” that Gore was too much a smarty-pants to be president. That weekend Saturday Night Live spoofed them to great effect. The debate that Gore had won in real time was, within days, a debate he’d lost.

Candidates need not only to master the issues. They need to master performance. Cable television will replay clips; the candidate who wins the battle of the clips will be the 72-hour winner. The substance doesn’t matter as much as the theatre. McCain will, for instance, surely needle Obama on the experience question. Obama had better have a sharp and snappy reply to that. If he doesn’t, he could lose the 72-hour debate in that single exchange. This isn’t the democracy Thomas Jefferson had in mind. But as Donald Rumsfeld might say, it’s the one we have. — The Guardian