World Bank President Robert Zoellick said on Wednesday he will step down in June and Washington pledged to put a replacement candidate forward within weeks for a job that has always gone to an American.

World Bank President Robert Zoellick takes his seat before delivering the 2011 McNamara Lecture on War and Peace at the John F. Kennedy School of Government at Harvard University in Cambridge, Massachusetts in this November 29, 2011 file photo. [Photo/Agencies]

The Obama administration said it would open the process to competition, marking the first time it has shown willingness to loosen its grip on the world's top development lender.

Zoellick took the reins at the Bank in 2007 after a staff revolt pushed out Paul Wolfowitz, and he moved quickly to return the institution's focus to alleviating poverty.

Developing countries have for years pressed for a greater voice in leading global financial institutions and are likely to stress the importance of a competitive process, but the United States is still widely expected to retain its hold on the job.

"It is very important that we continue to have strong, effective leadership of this important institution, and in the coming weeks, we plan to put forward a candidate with experience and requisite qualities to take this institution forward," US Treasury Secretary Timothy Geithner said in a statement.

While Geithner called for an "open and expeditious process," analysts say Washington can ill afford to give up the post without risking the US Congress cutting funding for the Bank.