They work:
Perry leads in the polls, while Bachmann and Paul trail substantially. As the model predicts, trailing candidates are attacking the front-runner. Why? Because these candidates improve their relative position in the polls more by undermining Perry’s support than by trying to attract undecided voters. … Perry is not somehow nobler for “taking the high road.” Rather, candidates are simply responding to the electoral incentives they face. In this particular case, trailing candidates need to attack.
The Dish 