"It's a problem, frankly, that I think the administration will face in general as we go forward," said U.S. Defense Secretary Robert Gates. "There (are) roughly 20 months left in this administration. To ask somebody to come in, to ask them to go through a divestiture process in terms of their personal financial holdings, to go through the entire investigative process, and by the time they're finally on board, to spend 15 months doing the job, it's a challenge finding people who are willing to do something for that period of time," he said.

"When you add a confirmation process on top of all of that, it's a real challenge. And so I think finding somebody who is willing to do all of that for a finite -- for the kind of time that's available has been one of the challenges," Gates said.

Gates himself only joined the Bush administration in December, with just two years left and two difficult wars to manage.

At least three former generals have already turned down the job, which Gates likens to a "911" line for the military in Iraq who need specialized personnel or interagency support and are not getting it quickly enough.

The job would be "somebody operating out of the White House, empowered by the president, who can call up and say, 'You were asked to provide this number of people with this kind of a speciality, and the president wants to know where they are,'" Gates said.