With recent US poll numbers showing the lowest support for the Iraq War to date and with so many Republicans jumping ship (speaking out against staying the course and for a timetable for withdrawal), Bush doesn't have the political capital anymore to attack Iran.
He knows it now. He knows that he has lost all credibility. If he set up a false-flag operation to blame Iran and then attacked Iran, he would sink the Republican Party for good. He knows that too. How pragmatic can he be? So far, he hasn't shown any real sense. Is he rash enough to attack Iran anyway?