Photo gallery: First Democratic presidential debate

Hillary Rodham Clinton smiles during the CNN Democratic presidential debate Oct. 13, 2015, in Las Vegas.

Democratic presidential candidate Sen. Bernie Sanders speaks Oct. 13, 2015, during the first Democratic presidential debate in Las Vegas.

Presidential candidates Martin O’Malley, left, and Lincoln Chafee take part in the Democratic presidential debate Oct. 13, 2015, in Las Vegas.

Former U.S. Sen. Jim Webb from Virginia speaks Oct. 13, 2015, during the Democratic presidential debate in Las Vegas.  (John Locher / Associated Press)

Former Rhode Island Gov. Lincoln Chafee speaks Oct. 13, 2015, during the Democratic presidential debate in Las Vegas.   (John Locher / Associated Press)

Former Maryland Gov. Martin O’Malley speaks during the first Democratic presidential debate Oct. 13, 2015, in Las Vegas.  (John Locher / Associated Press)

U.S. Rep. Steven Horsford, D-Nev., left, is among the crowd in a Democratic presidential debate Oct. 13, 2015, in Las Vegas.

Members of the audience wait for the beginning of the first Democratic presidential debate Oct. 13, 2015, in Las Vegas.  (Alex Wong / Getty Images)

Democratic presidential candidates from the left: Jim Webb, Bernie Sanders, Hillary Rodham Clinton, Martin O’Malley and Lincoln Chafee.