It doesn’t feel that long, but it was 20 years ago on Sunday that an inexperienced Republican candidate for vice-president – young, right-wing, good-looking, widely criticised as an intellectual lightweight – faced off in a debate against the experienced Democrat senator who was his opponent.

That debate, between Dan Quayle and Lloyd Bentsen, has obvious parallels with last week’s Palin-Biden showdown. In each case, Republican strategists were seriously worried beforehand that their candidate would be revealed as out of their depth. They tried to counter that by playing the “expectations game”: by spreading stories themselves about the candidate’s shortcomings to lower expectations, in the hope that the public would then see they were not as bad as they’d been painted.

For Quayle, it didn’t seem to work. Primed to expect a candidate who just wasn’t very bright, the public watched him and noticed that, well, he wasn’t very bright. Not that he was any worse than most politicians in that respect, but once you’re looking for lack of intellectual gravitas – and in Quayle’s case people were – it’s pretty easy to find.

With Sarah Palin, however, the expectations game looks to have worked fairly well. The difference seems to be that Palin, with even fewer credentials than Quayle, is unable to even make a pretence at gravitas.

Instead she’s been forced to rely on her other strengths.

Firstly, as a young frontier-state woman, Palin has an exotic glamor that diverts attention away from her intellect or experience. Quayle’s supposed likeness to Robert Redford was not in the same league. When he tried to make a virtue of his youth, Bentsen blew him out of the water with “Senator, you’re no Jack Kennedy.”

Secondly, Palin is a much more fully-fledged ideological warrior. As the darling of the religious right, she commands a more devoted allegiance than Quayle ever did; they will defend her come what may, and the media have to take account of that – their influence in the Republican party is a lot stronger than it was 20 years ago.

What is the moral of all this? On one view, it’s that the running mate doesn’t matter; Bentsen won the debate, but Bush and Quayle went on to win the election comfortably.

On the other hand, the GOP in 1988 was coming off a landslide: the Democrats got a 5.3% swing. If Obama gets just a fraction of that, he’s going to be president, and Sarah Palin will be heading back to Juneau.