Preston Murdoch Geren III was born in Fort Worth, Texas on 29 January 1952 (the brother of Republican Party politician Charlie Geren), and he played football at Georgia Tech before earning his juris doctor from the University of Texas Law School in 1978. He worked as an attorney and businessman in Fort Worth before being elected to the US House of Representatives in 1989 as a Democratic Party member. Geren, a conservative, coined the term "Blue Dog Democrat". In 2001, he was employed by the Department of Defense as a special assistant to the Defense Secretary, and he was acting Secretary of the Air Force for a few months in 2005. George W. Bush went on to nominate him to be US Secretary of the Army in 2007, and he served until 2009. Geren went on to serve as President of the Sid W. Richardson Foundation in Fort Worth after 2011.