Not necessarily. The Dems would scream, "You see! You see! We told you so!" And the Republicans would only have, "Hey, you didn't like anything we were proposing." Either way there would be alot of dead people and devasation. But remember that the Islamonazis go by their 7th century calculations of time, not that of the infidel, and they're very into symbolism.
There wouldn't have enough calendar time for that to work. The dems wouldn't be able to get much of a message out because the MSM would be on it with non-stop coverage and the country rallying around the prez. So a terrorism attack helps the party in power until enough time elapses for everything to settle down and the other side starts the blame game. Thats what happened after 9/11 and would likely play out again.