COLUMBIA, SC - JANUARY 18, 2016: Democratic presidential candidates, former Maryland Gov. Martin O'Malley, right, and Sen. Bernie Sanders, I-Vt, left, walk in the annual King Day at the Dome parade Monday, January 18, 2016 in Columbia, South Carolina. The parade concluded at the S.C. State House and 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)