Winning an election is all about advertising and it’s all in the message. McCain is using the tried and true Republican message which is attack the opponent. This message has worked very well in the past, but is not working now. Attacking the opponent works when the population is happy. When things are not going well, this type of strategy does not work.
When people are unhappy, a political candidate must explain what can be done to make things better. When people are already happy, changing things can only present risk. Thus, attacking your opponent becomes an effective strategy.