Democratic presidential candidate Sen. Bernie Sanders, I-Vt., former Vice President Joe Biden, center, and Sen. Elizabeth Warren, D-Mass., rig…

Democratic presidential candidate former Vice President Joe Biden, left, Sen. Elizabeth Warren, D-Mass., center and South Bend Mayor Pete Butt…

Democratic presidential candidate Sen. Elizabeth Warren, D-Mass., speaks in a Democratic presidential primary debate hosted by CNN/New York Ti…

The stage is prepared where the CNN/New York Times will host the Democratic presidential primary debate at Otterbein University, Tuesday, Oct.…

Democratic presidential candidates chosen to participate in fourth debate;

Democratic presidential candidate Sen. Bernie Sanders, I-Vt., left, listens as former Vice President Joe Biden speaks during a Democratic pres…

Democratic presidential candidate Sen. Bernie Sanders, I-Vt., left, and former Vice President Joe Biden shake hands following a Democratic pre…

Democratic presidential candidate Sen. Amy Klobuchar, D-Minn., responds to questions following a Democratic presidential primary debate hosted…

Democratic presidential candidate Sen. Kamala Harris, D-Calif., left, Sen. Bernie Sanders, I-Vt., middle, and former Vice President Joe Biden …

Democratic presidential candidate Sen. Cory Booker, D-N.J., left, speaks as Sen. Kamala Harris, D-Calif., listens during a Democratic presiden…