McAlister became Nashville's assistant city attorney in 1901, and was elevated to city attorney in 1905. He was elected to the Tennessee Senate in 1910, and served two terms (1911–1915). As a state senator, he sought stricter enforcement of laws regarding education and child labor, and advocated better food and drug inspections. He also sought funding for a tuberculosis hospital for Nashville. McAlister was an elector for President Woodrow Wilson in 1916, and served on the state Democratic Executive Committee from 1918 to 1920.