The main US fear in the current political dispute is that an election likely would be won by Shiite Muslims, long persecuted by Saddam Hussein's regime. That could lead to a civil war if it is met by revolt among Iraq's Sunni Muslims, who brutally suppressed the Shiites under Saddam, and among Kurds, who have enjoyed near autonomy under protection of US and British warplanes that enforced a no-fly zone over Iraq.
Another nightmare scenario, analysts say, is that the Shiite majority might insist on Islamic law, doing away with freedoms Iraqis had during Saddam's brutal, but secular, rule.
The UN has experience in working with transitional governments, setting up elections, and other areas that fit the bill in Iraq.
"The administration is implicitly admitting it made a mistake in not getting the UN involved politically in Iraq earlier on," said James Lindsay a foreign policy and defense expert at the Council on Foreign Relations.