Rajiv Shah, a medical doctor who holds a senior position at the Agriculture Department dealing with food security, will bring "fresh ideas" and an "impressive background" to the U.S. Agency for International Development, President Barack Obama said in a statement announcing the nomination.

Shah's selection, which requires Senate confirmation, would end a 10-month leadership vacuum at USAID, which has been operating with an acting director since Obama took office despite his campaign pledges to have the agency play a greater role in foreign policy.

Obama and Secretary of State Hillary Rodham Clinton have said USAID is crucial to deploying their preferred "smart power" foreign policy strategy, which envisions more equal roles for diplomacy and development alongside defence. They plan to double the amount of foreign aid.

The agency will play a key role in the administration's efforts in Afghanistan and Pakistan, where officials believe the civilian component must be strengthened.

The top job at the agency has remained vacant until now, with several prime candidates withdrawing from consideration amid a White House vetting process that Clinton denounced in July as "ridiculous," "a nightmare" and "frustrating beyond words."

For many in international development, Shah's nomination was a welcome and overdue.

"It's about time," said Samuel Worthington, president of Interaction, a coalition of humanitarian organizations.

Shah, 36, whose family immigrated to the United States from India, is now the Undersecretary for Research, Education and Economics and Chief Scientist at the Agriculture Department where he manages a budget of more than $2.6 billion and more than 10,000 staff around the world.

Before that, Shah had several positions at the Gates Foundation, including managing its $1.5 billion contribution to a global vaccination fund and helping launch the foundation's Global Development program where he oversaw a $1.3 billion investment portfolio.

The lingering USAID vacancy, particularly after several leading candidates pulled out, prompted Sen. John Kerry, chairman of the Senate Foreign Relations committee, and Sen. Dick Lugar, the committee's top Republican, to send Obama a letter suggesting he choose someone who already had gone through the vetting process.

Shah fits that bill and has important political credentials, having worked for several leading Democratic politicians.

In a joint statement, Kerry and Lugar praised the nomination and said they look forward to a thorough confirmation process.

If confirmed, Shah will take over a weakened agency that has seen its staff cut and some functions folded into the State Department. Many in international development worry that State plans to keep control of the aid agency's budget, with the new administrator answering to a deputy secretary of state.

Given that speculation, and the delay in appointing an administrator, David Beckmann, co-chairman of the Modernizing Foreign Assistance Network, said the administration needs to move quickly in defining Shah's responsibilities.