Earlier this year, retired Air Force General Scott Gration was said to be favoured for the position of Nasa administrator.

BBC: Obama names US space agency chief

So I've appointed a special envoy, a Major General Scott Gration, a very close friend of mine, was one of the top fighter pilots in our military, in our Armed Forces, and somebody who's also an expert on development issues.

WHITEHOUSE: Town Hall in Arnold, Missouri

At the same time, a variety of other mediators, including the Qataris and a new American special envoy to Sudan, Scott Gration, have been encouraging the disparate rebel groups to resolve their differences and form a more coherent negotiating body.

ECONOMIST: The crisis in Darfur