Democratic presidential candidates at CNN Iowa town hall

Democratic presidential candidate Hillary Clinton participates in the CNN Democratic candidates town Hall event at Drake University in Des Moines, Iowa,o n January 25, 2016.

Democratic presidential candidate Hillary Clinton speaks during a CNN town hall at Drake University in Des Moines, Iowa, on Jan. 25, 2016.

Sen. Bernie Sanders (I-VT) speaks at a town hall forum hosted by CNN and moderator Chris Cuomo at Drake University on Jan. 25, 2016, in Des Moines, Iowa.

Democratic presidential candidate, Sen. Bernie Sanders, I-Vt., speaks during a CNN town hall at Drake University in Des Moines, Iowa, on Jan. 25, 2016.

Former Maryland governor and Democratic presidential candidate Martin O’Malley shakes hands with members of the audience after speaking during the CNN Town Hall at Drake University in Des Moines, Iowa, on January 25, 2016.

Former Maryland Governor and Democratic Presidential Candidate Martin O’Malley (L) speaks during the CNN Town Hall at Drake University in Des Moines, Iowa, on January 25, 2016.