President Bush suffered an undeniable setback in Iraq when drafters failed to agree on a new constitution by the Aug. 15 deadline in spite of the strenuous efforts of U.S. envoy Zalmay Khalilzad and Defense Secretary Donald Rumsfeld.

The National Assembly voted to give the negotiators another week to finish a final draft of the constitution, which itself involved amending the interim constitution.

Sticking to the timetable is critical to administration hopes of winding down the U.S. military presence next year. The constitution is to be put to a referendum Oct. 15, followed by parliamentary elections Dec. 15, with a new, popularly elected government _ to which the United States can hand over the keys and responsibility for fighting the insurgents _ taking power Dec. 31. It is a tight schedule with little room for error.

A stumble at any stage would mean a major U.S. military presence, and presumably continuing casualties, through the 2006 elections.

The constitutional differences that remain are few but critical _ the rights of women, the role of Islam, the division of oil revenues and Shiite and Kurdish demands for regional autonomy, an effective partitioning of Iraq. From a distance, it is hard to tell from the contending parties what is posturing and poker-playing and what are irreconcilable differences.

The best outcome would be for the negotiators to come to an agreement. If they don’t, the interim constitution calls for dissolving parliament and holding new elections. While the Sunnis seem to have learned their lesson about boycotts, it is probably too much to hope for another purple-finger miracle.

The worst outcome would be for Iraq to dissolve into bloody factionalism, which the United States would be powerless to stop. That could mean a Shiite theocracy tied to Iran in the south; an autonomous Kurdish state in the north that Turkey would see as a provocation; and an embittered, impoverished Sunni minority in the middle with Syria as its only friend, all living in a constant state of low-level civil war.

The Iraqi people have proved resilient, flexible and inventive, so the worst may well not happen and the negotiators will pull back from the brink and act in the national interest. But it may also be that the fate of Bush’s Iraq venture depends on the events of this week.

(Contact Dale McFeatters at McFeattersD(at)