Kirk, who has headed the agency since March 2009, was elected in 1995 as the first African-American mayor of Dallas. He left that job in 2001 in an unsuccessful bid for the U.S. Senate in 2002. Kirk has also been a partner in the international law firm of Vinson & Elkins.
Kirk most likely is headed for a private sector position back home in Dallas.
Possible successors include Fred Hochberg, a businessman who had been acting Small Business Administration chief in the Clinton Administration and is now chairman of the Export-Import Bank; Francisco Sanchez, currently Commerce undersecretary for international trade and before that assistant secretary of transportation in the Clinton administration; and Jeff Zients, former CEO of The Advisory Board Co. and now acting director of the Office of Managment and Budget.