AQ wants to have an impact on the election, do something which affects the outcome in a way that is favorable to them. A President Kerry who would not wage war against terror but rather issue arrest warrants that could never be executed and ask the UN to condemn attacks is the election result AQ wants. They know that an attack in the U.S. probably would rally support arount the President and foil Kerry's chances. They also know that the Iraq body count is the Presidents biggest vulnerability. Iraq is where AQ will try to make their next big mass casualty attack happen I think, or at a U.S. military facility somewhere else outside the U.S. if they can't pull it off in Iraq.
Don't count on W getting a Poll boast , if there is an another attack.
Rats will blame W for not protecting the HOMELAND and
Americans might Belief them.