Al Jazeera's Tony Harris speaks to James Boys, an expert on the US electoral system about whether this election has seen a rise in negative campaigning by the two parties.

Boys, speaking from London, said so far, this year's election has noot been "particularly problematic" and that "unfortunately, negative has been shown to work" in the past.

Boys said though campaigns try to draw a distinction between the officially-sanctioned ads, approved by the candidates themselves, and the ones by political action committees, PACS, "they're both trying to do the same things. They're both after the same votes, they're both trying to have the same affect".