Byrnes left the Supreme Court to head Roosevelt 's Office of Economic Stabilization , which dealt with the vitally important issues of prices and taxes . How powerful the new office would become depended entirely on Byrnes 's political skills , and Washington insiders soon reported he was fully in charge . In May 1943 , he became head of the Office of War Mobilization , a new agency that supervised the Office of Economic Stabilization . Under the leadership of Byrnes , the program managed newly constructed factories across the country that utilized raw materials , civilian and military production , and transportation for U.S. military personnel and was credited with providing the employment needed to officially bring an end to the Great Depression . Thanks to his political experience , his probing intellect , his close friendship with Roosevelt , and in no small part to his own personal charm , Byrnes was soon exerting influence over many facets of the war effort which were not technically under his departmental jurisdiction . Many in Congress and the press began referring to Byrnes as the " Assistant President . " Many expected that Byrnes would be the Democratic nominee for vice president with Roosevelt in 1944 , replacing Henry A. Wallace , who party officials strongly felt was too eccentric to replace an ailing president who likely was going to die before his next term ended . Roosevelt refused to endorse anybody other than Wallace . He had a personal preference for U.S. Supreme Court justice William O. Douglas . Byrnes was on Roosevelt 's list but hardly his first choice . In a July meeting at the White House , the party bosses pressed hard for Senator Harry S. Truman of Missouri , and Roosevelt issued a statement saying he would support either Truman or Douglas . Byrnes was regarded as too conservative for organized labor , the big city bosses opposed him as an ex-Catholic who would offend Catholics , and blacks were wary of his opposition to racial integration . In short , Byrnes never had a serious chance at being nominated for vice-president , and the nomination went instead to Truman . Roosevelt brought Byrnes to the Yalta Conference in early 1945 , where he seemed to favor Soviet plans . Written in shorthand , his notes comprise one of the most complete records of the " Big Three " Yalta meetings
Yalta Conference
Yalta Conference
James F. Byrnes