GWEN IFILL: Now: Haiti's leader comes to the United States two months after the earthquake -- on his agenda, more aid for his hard-hit nation.
Ray Suarez has our story.
RAY SUAREZ: The White House was the critical stop on President Rene Preval's Washington tour, and he won a renewed commitment from President Obama.
U.S. PRESIDENT BARACK OBAMA: As you declared during last month's national day of mourning, it is time to wipe away the tears. It is time for Haiti to rebuild. And to you and to the Haitian people, I say today, as you embark on the heavy work ahead, you will continue to have a steady and reliable partner in the United States of America.
RAY SUAREZ: Like much of the Haitian capital, Preval's own White House lies in ruins, crushed by the January 12 quake that killed an estimated 230,000 and left more than 1.2 million homeless.
Mr. Obama lent some perspective:
BARACK OBAMA: It's as if the United States, in a terrible incident, lost nearly eight million people, or it's as if one-third of our country, 100 million Americans, suddenly had no home, no food, or water.
RAY SUAREZ: Preval thanked Americans for their public and private efforts and asked for continued assistance.
RENE PREVAL, Haitian president (through translator): We must deal with the need of rebuilding Haiti, thanks to an effective decentralization policy, namely, offering health care, education, jobs to all Haitians, men and women, regardless of where they live in the country, in order to prevent migratory flows towards the big cities.
RAY SUAREZ: The U.S. government has already delivered $700 million in assistance. Nearly half of U.S. households have given money to other aid efforts. And there's a United Nations meeting later this month, where aid pledges from an earlier post-quake conference in Montreal will be solidified.
On the ground in Haiti, eight weeks on from the quake, the rainy season has come early, adding to the misery. Already-cramped camps, turned into a squalid mess, are ripe for festering disease and a possible second catastrophe.
MAN (through translator): Look, we don't have any other place to go.
RAY SUAREZ: Hundreds of thousands displaced by the January quake live in the sprawling tent and tarp cities around the capital, Port-au-Prince. Though officials say nearly half have received some type of shelter, they face a future as uncertain as Haiti itself.
In the Champ de Mars camp outside the shattered presidential palace, aid workers recently registered the displaced, and tried to persuade the weary homeless to move elsewhere.
VLACKOV ABRAMOSKIEV, supervisor, International Organization for Migration: This means that preparing maybe their home sites, cleaning the rubble, maybe preparing some other safer places, because rainy season is coming, and it's really not safe for the people to stay there.
RAY SUAREZ: President Preval himself will soon be moving on, after a fashion. His term ends next February, and he is not seeking reelection.
In the year left to him, ensuring parliamentary elections later this year, canceled because of the quake, is a priority, and rebuilding a government that had 13 of its 15 ministries flattened is a monumental task.
Meantime, the U.S. military is steadily withdrawing forces it deployed to Haiti. At the peak, 20,000 U.S. personnel were there. Eight thousand remain, and that number will shrink further. Their departure has raised concerns.
ALISON THOMPSON, nurse: It is big trouble. The 82nd Airborne have been amazing. They have been giving food, shelter, medical, everything. But they are all pulling out. We had 400 of our guys pull out five days ago.
We have got 60 left, but 30 are going in the next few days. Soon, we are going to have no security here. And that's the most important thing, is the U.S. presence in Haiti. It's going to be shocking when they leave, just security, for a start, on top of everything else.
RAY SUAREZ: Despite those fears, the United Nations says its peacekeeping force, in Haiti before the quake, will ensure security going forward.