"He’s a very well respected figure. Your campaign is essentially fighting with him now in a way that is casting aspersions on his character, calling him dishonest," Maddow told Clinton.
"No, no," the former secretary of state responded.
Maddow then asked Clinton, "He won’t level with the American people?"
In response, Clinton noted that Sanders' campaign hasn't revealed details about what his health care proposal would cost.
"For months his campaign has been saying before the Iowa caucus we will tell you what we are proposing in taxes. And the bulk of what he is advocating for is a single payer health care system, which would probably cost about $15 trillion," she said, lamenting that voters will not be able to compare the candidates' two plans before the Iowa caucuses.
"Do you disagree with that goal?" Maddow then asked. "Do you disagree with single payer as a good -- I guess it would be too hard to do."
Clinton said she agrees with universal health care.
"But to me, the Affordable Care Act is one of the signature accomplishments, not just of this president, but of the Democratic Party," she said.
"Now, the only clue that I can find, because he hasn’t laid out a plan, is to go back and look at the bills that he’s introduced nine different times. And it’s a bit concerning to me because it would basically end all the kinds of health care we know, Medicare, Medicaid, the CHIP program, children’s health insurance, TRICARE for the National Guard, military, Affordable Care Act exchange policies, employer-based policies," Clinton added. "It would take all that and hand it over to the states."
Watch the interview from MSNBC. Maddow brings up Clinton's criticisms of Sanders near the 8:45 mark.