It is a case of the relatively novice Republican against the experienced Democrat: she who says it is time for a change of the old guard in Washington; he who says experience and knowledge in troubled times is crucial.
Amid continuing bad press about her competence, Sarah Palin has been pulling no punches. “I’ve never met him before,” she said. “But I’ve been hearing about his Senate speeches since I was like in second grade.”
Observers say there is no doubt that Joe Biden knows his stuff. But Palin has had lots of homework to do. Her party has tried to boost her knowledge of world affairs, as TV shows make fun of her as a moose-hunting, hockey-mum from Alaska. Suddenly she has had to be across thorny issues like Iran.
She recently told an interviewer: “The bad guys are the ones who say Israel is a stinking corpse and should be wiped off the face of the earth. That’s not a good guy who is saying that.”
Palin is popular, though, among social conservatives, Christians and female voters. Her party just has to hope there is no gaffe that jeopardises that.
Robert Shrum, a political strategist, said: “If Sarah Palin has a moment where she reveals that she is way out of her depth, it’s not only going to hurt her, it’s going to reflect very badly on John McCain’s judgement. So there is going to be an effort made here to give her a set of standard answers and hope she can skate by with them.”
Meanwhile, commentators say Biden must reassure people that his many years in Congress will not be a hindrance to change. And while some say he should not be soft and condescending during the debate, others say he should also think twice before going on the attack.
Peter Kastor, a Washington University professor, said: “If Joe Biden goes over the top in his tone, in the content of what he says, there could be a chorus of criticism against him, claiming that he was being unduly antagonistic towards a female candidate.”
Campaign managers have had a close hand in controlling how candidates come across to the public – but there is little they can do if things start to go wrong on live television.