BBC Panorama/screenshot
But one topic - and person - produced a clear divide: Edward Snowden and National Security Agency surveillance.
The Democratic front-runner and former secretary of state, Hillary Clinton, unequivocally rejected the characterization of Snowden by many as a "whistleblower."
She said Snowden should return to the US and "face the music."
"He broke the laws of the United States. He could have been a whistleblower. He could have gotten all of the protections of being a whistleblower," Clinton said.
"He could have raised all of the issues that he has raised. And I think there would have been a positive response to that. In addition, he stole very important information that has unfortunately fallen into a lot of the wrong hands. So I don't think he should be brought home without facing the music."
Former Maryland Gov. Martin O'Malley (D) agreed. He said Snowden put US "lives at risk" and questioned his decision to "run to Russia."
"Snowden put a lot of Americans lives at risk. Snowden broke the law. Whistleblowers do not run to Russia and try to get protection from Putin. If he really believes that, he should be back here," O'Malley said.
But Sen. Bernie Sanders (I-Vermont), the race's liberal insurgent, took a more sympathetic view of Snowden and pledged to end the NSA's surveillance programs as they are currently constructed.
I think Snowden played a very important role in educating the American people to the degree in which our civil liberties and our constitutional rights are being undermined. He did break the law and I think there should be a penalty to that. But I think what he did in educating us should be taken into consideration before he is sentenced.
Lincoln Chafee, the former governor and US senator from Rhode Island, agreed and said he would bring Snowden home.
"No, I would bring him home. … The American government was acting illegally, that's what the federal courts have said," Chafee said.
Finally, former Sen. Jim Webb (D-Virginia) said that though he believes there's a "serious problem" with the NSA's programs, the final word on Snowden should rest with the US legal system.
"I would leave his ultimate judgment to the legal system," he said. "Here's what I do believe: We have a serious problem in terms of the collection of personal information in this country."