COLUMBIA, SC - JANUARY 18, 2016: Democratic presidential candidate Sen. Bernie Sanders, I-Vt, marches in the King Day at the Dome parade Monday, January 18, 2016 in Columbia, South Carolina. The event drew appearances from Democratic presidential candidates Sen. Bernie Sanders, I-Vt, former Maryland Gov. Martin O'Malley and Hillary Clinton. (Photo by Sean Rayford/Getty Images)