4th Democratic debate
Democratic presidential hopefuls square off in South Carolina in their 4th debate ahead of the Iowa caucus, January 17, 2016.
(L-R) former Governor Martin O'Malley, former Secretary of State Hillary Clinton and U.S. Senator Bernie Sanders pose together before the start at the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
Hillary Clinton & Bernie Sanders
Sen. Bernie Sanders, I-Vt., gestures towards Democratic presidential candidate, Hillary Clinton during the Democratic presidential debate at the Gaillard Center, January 17, 2016, in Charleston.
This is the final debate for the Democratic candidates before the Iowa caucuses.
Hillary Clinton & Bernie Sanders
Former Secretary of State Hillary Clinton (L) and Vermont Senator Bernie Sanders (R) participate in the NBC News -YouTube Democratic Candidates Debate on January 17, 2016 at the Gaillard Center in Charleston.
Martin O'Malley & Hillary Clinton
Former Governor Martin O'Malley speaks as former U.S. Secretary of State Hillary Clinton looks on in Charleston, January 17, 2016.
Bernie Sanders
U.S. Senator Bernie Sanders speaks at the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
Sanders advocated universal health care in what he termed "Medicare for all."
Hillary Clinton
Former Secretary of State Hillary Clinton speaks at the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
All three candidates hotly debated the future of American health care. Clinton praised the many improvements created by the Affordable Care Act, but said she wanted to work to improve it.
Democratic debate
Former Governor Martin OMalley (L), Hillary Clinton (C) and Senator Bernie Sanders (I-VT) stand on the state at the Democratic debate January 17, 2016 in Charleston.
Hillary Clinton & Bernie Sanders
Former Secretary of State Hillary Clinton (L) and rival candidate Senator Bernie Sanders (R) speak simultaneously at Democratic presidential candidates debate in Charleston, January 17, 2016.
Martin O'Malley
Former Governor Martin O'Malley (L) chats with moderators Lester Holt (C) and Andrea Mitchell during a break at the Democratic Debate hosted by NBC News and YouTube on January 17, 2016 in Charleston.
Bernie Sanders
Senator Bernie Sanders (I-VT) fields a question from moderators Lester Holt (C) and Andrea Mitchell during the Democratic debate on January 17, 2016 in Charleston.
Democratic debate
Former Secretary of State Hillary Clinton, center, delivers her opening statement at the NBC, YouTube Democratic presidential debate at the Gaillard Center in Charleston, January 17, 2016. To the left is former Maryland Gov. Martin O'Malley and to the right Democratic presidential candidate, Sen. Bernie Sanders, I-Vt.
When asked about working with Russian President Vladimir Putin, Clinton described their relationship as "interesting."
Hillary Clinton & Bernie Sanders
Former Secretary of State Hillary Clinton (L) and rival candidate Senator Bernie Sanders (R) speak simultaneously at the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
Clinton repeatedly embraced the achievements of the Obama administration.
Martin O'Malley
Former Governor Martin O'Malley speaks at the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
Democratic debate
(L-R) Former Governor Martin O'Malley, former Secretary of State Hillary Clinton and Senator Bernie Sanders pose together before the start of the NBC News - YouTube Democratic presidential candidates debate in Charleston, January 17, 2016.
Hillary Clinton
Former Secretary of State Hillary Clinton arrives on stage for the Democratic candidates debate on January 17, 2016 at the Gaillard Center in Charleston,
Democratic debate
Former Maryland Gov. Martin O'Malley , left, Democratic presidential candidate, Hillary Clinton and Democratic presidential candidate, Sen. Bernie Sanders, I-Vt, stand together before the start of the NBC, YouTube Democratic presidential debate at the Gaillard Center, January 17, 2016, in Charleston.
Democratic debate
Former Maryland Gov. Martin O'Malley , left, Democratic presidential candidate, Hillary Clinton and Democratic presidential candidate, Sen. Bernie Sanders, I-Vt, stand together before the start of the NBC, YouTube Democratic presidential debate at the Gaillard Center, January 17, 2016, in Charleston.
Hillary Clinton
Former Secretary of State Hillary Clinton walks across the stage during a break at the Democratic presidential candidates debate in Charleston, January 17, 2016.
Democratic debate in Charleston
A group of signs for Democratic presidential candidates Bernie Sanders and Hillary Clinton before the start of the NBC News -YouTube Democratic Candidates Debate on January 17, 2016, at the Gaillard Center in Charleston, South Carolina.
Democratic debate in Charleston
Demonstrators protest in front of supporters of Democratic presidential candidate Hillary Clinton as they rally outside the Gaillard Center before the start of the NBC News Democratic Candidates Debate on January 17, 2016 in Charleston, South Carolina.
This is the final debate for the Democratic candidates before the Iowa caucuses.
Democratic debate in Charleston
Supporters of Democratic presidential candidate Hillary Clinton rally outside the Gaillard Center before the start of the NBC News Democratic Candidates Debate on January 17, 2016 in Charleston, South Carolina.