He moved to Memphis, Tennessee and is related to Henry Nickey, an MUS Basketball star, and was admitted to the state bar the same year.

McKellar joined the Democratic Party, which dominated the politics of West Tennessee, where plantations were historically and economically important.

[2] McKellar was considered a moderate progressive in his early days in the Senate, and he supported many of President Woodrow Wilson's reform initiatives as well as ratification of the Treaty of Versailles.

During President Franklin D. Roosevelt's administration, McKellar staunchly supported the New Deal, especially the creation of the Tennessee Valley Authority (TVA), to provide flood control and generate hydropower for rural electrification in the Tennessee Valley.

Despite his early support for the policies of Franklin D. Roosevelt (FDR), McKellar became more conservative in his political stances.

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.

Lilienthal was also closely associated with the Manhattan Project's work to electromagnetically enrich uranium, coincidentally at the facility later known as Y-12.

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.

By the time the law came into effect, McKellar was no longer in the position of President pro tempore, as the Republicans had gained the majority in the 80th Congress.

Except for McKellar, Tennessee has generally not joined in the Southern tradition of reelecting senators for protracted periods of service.

Most African Americans had been disenfranchised by discriminatory laws and practices, resulting in the Republican Party being active chiefly in East Tennessee.

Browning, who had served a total of three terms as governor, the last two successive, had also at one point been a close ally of Crump's but had since broken ranks with him.