feud with FDR's appointee to head the TVA, David E. Lilienthal. As ranking member of the Appropriations Committee McKellar, who was an avid supporter of property rights, successfully forced the TVA to properly reimburse landowners whose property was taken over by the TVA for such purposes as dam building and creation of lakes or reservoirs. Prior to McKellar's threats to withhold Federal appropriations for the purchase of uranium early in World War II, the TVA was commonly offering to give landholders "pennies on the dollar" for their properties. As head of the Appropriations Committee, McKellar knew about the appropriations needed for the Manhattan Project to build an atomic bomb. He was often called upon to "keep the secret" of the Manhattan Project by mingling funds for the bomb project with other projects, or through carefully planned (secret) War Projects Funding. As the Tennessee Valley Authority was centered in Tennessee, his home state, McKellar reacted to what he thought was harsh TVA treatment of his constituents as a personal affront by Lilienthal. McKellar's threat to withhold funding for purchases of uranium had a much deeper meaning, though. Lilienthal was also closely associated with the Manhattan Project's work to electromagnetically enrich uranium, coincidentally at the facility later known as Y-12. Ernest Lawrence's "electromagnetic" enrichment of uranium at Oak Ridge would eventually use the electricity created by the TVA to enrich the uranium used in the atomic bomb dropped on Hiroshima. By threatening to withhold funding for the purchase of uranium, McKellar was demonstrating to Lilienthal that the politician, as ranking member and Acting Chairman of the Appropriations Committee, held the power. He forced Lilienthal to have the TVA pay fair market value for land it appropriated. McKellar twice served as President pro tempore of the United States Senate. Beginning in 1945, he was the first to hold the position under the seniority system that has prevailed since of reserving it for the majority party. When Harry Truman became president in April 1945, upon FDR's death, the vice presidency became vacant. (The mechanism for filling intra-term vacancies had not yet been created by the 25th Amendment.) McKellar became the permanent Presiding Officer of the United States Senate. Also, as the President pro tempore of the Senate had, prior to 1886, been second in the presidential line of succession, behind only the vice president, Truman viewed McKellar as the logical wartime replacement for himself,