I would say not likely, because it would hurt their interests bigtime. If such a thing did happen you could expect the dems to immediately blame it on republicans, saying they allowed it to happen because we are distracted in Iraq. I don't think it would fly with the voters though, and such talk would backfire.
See, that's pretty much what I was thinking, however, I know the terrorists don't think logically like you and I do (otherwise, they wouldn't be terrorists...).