Kammala wannan jumla: A shekara ta 1916, Sandlin ya kasance wakili ne ga
Babban Taron Jam'iyyar Democrat, wanda ya hadu a St. Louis, Missouri, don sake zabar Shugaban Amurka Woodrow Wilson na New Jersey da Mataimakin Shugaban Thomas R. Marshall na Indiana, don wa'adin su na biyu a ofis. A shekara ta 1944, ya kasance dan takarar shugaban kasa na karo na hudu na Franklin Roosevelt.