The perils of negative campaigning

As a brief follow-up to my last post, and to set the stage for tonight's debate, I want to highlight the risks posed by the recent intensification of the McCain campaign's attacks on Obama. Negative campaigning can sometimes work, but American voters tend to dislike it. (It would be interesting to see some data on whether this phenomenon extends to other countries. British voters may have liked David Cameron's early promises to end "Punch and Judy politics", but do not seem to mind its return all that much.)

This is one possible explanation of the sharp decline in McCain's favorability ratings, as shown here:

 

This puts McCain in an awkward position as he weighs whether to bring the personal attacks on Obama into the debate tonight. They may backfire, coming from the less popular candidate. And that risk will be intensified if voters hear about some of the uglier incidents at his campaign events, which involved supporters shouting "Kill him!" and "Terrorist!" as McCain and Palin assailed Obama.