As potential donors gather today at the United Nations to assemble a fund to help rebuild earthquake-battered Haiti, the White House is asking Congress for additional spending to contribute to the reconstruction effort.

Haiti is hoping to raise $3.9 billion at the March 31 donors' meeting to cover the initial, 18-month phase of what is certain to be a lengthy reconstruction. The estimated total rebuilding cost is $11.5 billion, the UN says.

More than 220,000 were killed in the magnitude 7 quake on January 12, and an estimated 2 million people are living in temporary shelters in Port-au-Prince or have moved away from the devastated capital to seek refuge elsewhere in Haiti. The earthquake caused an estimated $7 billion in damage.

President Obama is seeking more than $2.8 billion for relief and rebuilding in Haiti. His request, sent to Congress March 24, includes about $800 million for reconstruction-related work.

Funds targeted for rebuilding include $749.3 million for "reconstruction needs to provide essential services," such as housing, water, sanitation, and electricity infrastructure, as well as roads, bridges, and ports, the White House says.

Up to $120 million of that $749.3 million would be a U.S. contribution to an envisioned, multi-donor Haiti recovery trust fund. The White House request also includes $84.5 million to replace U.S. Embassy housing in Haiti damaged by the quake.

Other portions of the request include reimbursements to federal agencies for costs they incurred in relief work shortly after the quake, along with $212 million to put toward a multilateral plan to cancel Haiti's debt.