WASHINGTON

A FEW days after Rajiv Shah was sworn in as the head of the United States Agency for International Development, he stopped by to see its rapid response center, a high-tech command post for disaster relief, which on that day stood empty and still.

Twelve hours later, an earthquake devastated Haiti, and for the next two months the center became Dr. Shah’s round-the-clock home. A brainy, 37-year-old physician with little government experience, Dr. Shah suddenly found himself coordinating a desperate emergency relief effort under the gaze of President Obama.

The pace has barely let up since: catastrophic floods in Pakistan, the surge of aid workers into Afghanistan, a top-to-bottom review of American foreign assistance  all have heavily involved Dr. Shah, turning him into one of the administration’s most visible foreign policy players.

But for this politically astute son of Indian immigrants from Ann Arbor, Mich., who is now the highest-ranking Indian-American in the administration, it is his ambitious campaign to rebuild Usaid that will ultimately determine his success or failure in Washington.