FILE - In this Nov. 6, 2015, file photo Democratic presidential candidates Hillary Rodham Clinton, from left, Sen. Bernie Sanders, I-Vt., and former Maryland Gov. Martin O'Malley, smile after a Democratic presidential candidate forum at Winthrop University in Rock Hill, S.C.
FILE - In this Nov. 6, 2015, file photo Democratic presidential candidates Hillary Rodham Clinton, from left, Sen. Bernie Sanders, I-Vt., and former Maryland Gov. Martin O'Malley, smile after a Democratic presidential candidate forum at Winthrop University in Rock Hill, S.C. Chuck Burton AP
FILE - In this Nov. 6, 2015, file photo Democratic presidential candidates Hillary Rodham Clinton, from left, Sen. Bernie Sanders, I-Vt., and former Maryland Gov. Martin O'Malley, smile after a Democratic presidential candidate forum at Winthrop University in Rock Hill, S.C. Chuck Burton AP