"The kind of criticism that we've heard from Sen. Sanders about our president is something I expect from Republicans," Clinton said onstage in Milwaukee. "I do not expect from someone running for the Democratic nomination to succeed President Obama."
Sanders fired back that he worked with Obama as a senator and noted the progress made, but he defended his right to be critical of a sitting president.
"Madam Secretary, that is a low blow," Sanders responded. "But you know what, last I heard we lived in a Democratic society. Last I heard, a United States senator had the right to disagree with a president, including a president who's done such an extraordinary job."
"President Obama and I are friends," Sanders said. "It is really unfair to suggest I've been unsupportive of the president. I have been a strong ally with him on virtually every issue."
But Clinton, a former secretary of State, did not back off. She answered him that while there is nothing wrong with criticizing the president, "what I'm concerned about is not disagreement on issues ... calling a president weak, calling him a disappointment, calling several times that he should have a primary opponent when he ran for reelection in 2012 — you know, I think that goes further than saying we have our disagreements. ... Those kinds of personal assessments and charges are ones that I find particularly troubling."