Coronavirus threat hangs over Biden-Sanders debate

"We're at war with the virus," Biden added, speaking in a studio without an audience, as the Democratic Party and CNN limited access because of the medical threat.

Sanders endorsed the idea of calling up the National Guard to assist, though he focused much of his debate comments on what he labeled a 'dysfunctional' health care system, and the economic impact of the response.

"They're closing down bars, they're closing down restaurants," Sanders said, referring to moves by a series of states. "What happens to the workers there?"

Biden may have made the biggest headline of the debate by saying that he would name a black woman to the U.S. Supreme Court, and that he would pick a woman to be his running mate.

"I will in fact pick a woman to be Vice President," Biden said. "There are a number of women who are qualified to be President tomorrow."

Sanders also said that would be his inclination as well.

"For me, it is not just nominating a woman," Sanders told the CNN moderators, "it is making sure that we have a progressive woman, and there are progressive women out there."

Biden and Sanders also squared off over what's next in the Congress - which will be some sort of major economic stimulus package to help spur new growth.

Sanders said it cannot be anything which resembles the Wall Street bailout plan from 2008 - which Sanders opposed, and Biden supported - as Sanders has long charged that helped feather the next of Wall Street as opposed to Main Street.

After the debate was over, Sanders in an interview with CNN raised the question of whether the Tuesday primaries in Arizona, Ohio, Illinois and Florida should even proceed, saying it may not make 'a lot of sense.'

Biden is the favorite to win the majority of delegates on Tuesday, with an outside chance to maybe sweep all four states as well.

Biden won four states last week, and leads in a fifth (Washington State). Sanders won only a modified primary in North Dakota.