The US has said it will move "swiftly" to find a replacement for Paul Wolfowitz, who says he plans to quit as head of the World Bank on 30 June.
Mr Wolfowitz's time at the World Bank has received mixed reviews
Mr Wolfowitz will step down after he was caught up in a bitter row surrounding the promotion and salary of his girlfriend, Shaha Riza.
The World Bank said that Mr Wolfowitz had acted in good faith, but admitted that a "number of mistakes" were made.
UK Prime Minister Tony Blair has been mentioned as a possible replacement.
Mr Wolfowitz, a former US deputy defence secretary, was nominated for the World Bank job by President George W Bush.
"Traditionally, the American nominee has become the World Bank president," White House spokesman Tony Fratto said on Friday.
He added that the US wanted "to move swiftly in this process" and find a replacement for Mr Wolfowitz.
"We want to make sure that we are selecting the best individual for the job," Mr Fratto explained. "We want someone who has a real passion for lifting people out of poverty."
The World Bank, which has more than 180 member countries worldwide, helps fund development projects in developing nations and has taken a strong and vocal stance against corruption.
Mr Wolfowitz has been under severe pressure for weeks, and a number of European politicians called on him to step down.
Critics have argued that he was damaging the reputation of the bank at a time when it was trying to secure billions of dollars in international donations to help fund its projects over the next few years.
Although it is early days in the hunt for a replacement, UK Prime Minister Tony Blair has been mentioned by observers as one possibility.
Speaking on the BBC's Radio Five Live, Joseph Stiglitz, a Nobel prize winner and former World Bank vice president, said that Mr Blair was "one of the people that is clearly being discussed".
However, Mr Stiglitz said that it might suit the World Bank better if, rather than a politician with global connections, they had "someone with real experience in development".
"It would be good for the institution at this juncture if they had somebody who was an economist who really understood what development entailed and could work closely with the staff," he explained.
Speaking on Friday, Mr Wolfowitz said that he was grateful for the work of his staff at the World Bank.
"I've gotten a lot of very gracious comments, notes, emails from staff, and I'm grateful for that," he said.
"And I'm particularly grateful for the hard work they've put in the last two years."
Mr Wolfowitz came under fire after details emerged about his role in securing a pay rise for Ms Riza, who used to work at the bank.
When appointed to his post in 2005, Mr Wolfowitz notified the bank of a potential conflict of interest because of his relationship with Ms Riza, and asked to step aside from any decisions regarding her future.
Mr Wolfowitz then proposed that Ms Riza was moved to the US state department, where her pay and position would rise in line with her prospects at the World Bank.
Ms Riza was transferred, and her salary rose to about $193,000 (£98,000).
A panel of the World Bank later found that Mr Wolfowitz had provoked a "conflict of interest" and broken its code of conduct.