Iran believes that it can't lose, no matter what the final form of Iraq's new constitution is. It Iraq gives the Islamic clergy (which is dominated by Shias) lots of power, perhaps even veto power, like in Iran, that would be great. But even without that, the government would be dominated by Shias, giving the Shia majority in Iran an Arab ally they have never had. The Sunni majority in the region, especially the Sunni Arabs (the Kurds are also Sunni) have always sought to keep the Shia Arab majority in Iraq from being in charge. Now this has changed, all because the Americans removed the Sunni Arab dictator, Saddam Hussein, from power in Iraq.
