At least 20 people died on Sunday when a bomber detonated half a tonne of explosives outside the top-security civilian and military headquarters of the US-led administration.
The attack may intensify fears in the White House about the path the country may take after the expected 1 July handover of power to Iraqi authorities.
American occupation administrator Paul Bremer and members of the US-appointed Governing Council will meet UN head Kofi Annan in New York, seeking support for plans for a provisional government.
The Secretary-General may prove wary of endorsing a process the UN has had no role in formulating, and cautioned against expecting any definitive decision at Monday's New York meeting, calling it a "stage along the road".
But Annan may consent to an expected request from Bremer and Iraqi leaders to field a small delegation to determine whether elections are feasible or to help negotiate a compromise on the handover.
However, the Grand Ayat Allah Ali al-Sistani, Iraq's foremost Shia religious authority and a figure capable of marshalling mass resistance to any administration, rejects the plan for a transitional assembly selected by caucuses.
Al-Sistani has refused to support
US plans for regional caucuses
Fearing manoeuvres to undermine Shia influence, he insists on direct elections not in late 2005 as the Americans plan, but in the run-up to sovereignty.
The United States signalled on Friday it was open to modifying plans on the caucuses, but said the mid-year deadline would stand. Both Annan and US authorities believe it is impractical to hold general elections in the next six months.
In an election year and after the loss of 500 American lives, President George Bush could ill afford the rise of an avowedly anti-US administration.
Sunday's bomb mostly killed Iraqi workers, viewed as collaborators by the rebels, as they waited to enter. Two US contractors were also believed killed.