While negative campaigning and pointing out the weaknesses of one's opponent can be quite effective, there hasn't been a presidential election in my lifetime decided on that basis. (Off the top of my head, I can't think of an example of that happening, period.)Obviously, when a candidate loses, there are a hundred different reasons for the loss. But I don't think you have to go back any further than 2004 to see an example of negative campaigning winning an election. Is there any doubt that the Swift Boat ads that ran virtually nonstop in Ohio managed to switch at least a hundred thousand votes and thus swing the state and the election to George Bush?