WATCH: Clinton And Sanders Get Heated About Who Likes Obama More

CREDIT: AP Photo/Tom Lynn

Democratic presidential candidates Sen. Bernie Sanders and Hillary Clinton smile as they take the stage before a Democratic presidential primary debate at the University of Wisconsin-Milwaukee, Thursday, Feb. 11, 2016, in Milwaukee.

Thursday night’s wide-ranging Democratic debate on PBS ended with the two presidential candidates sparring over who has been sufficiently supportive of President Barack Obama.

Former Secretary of State Hillary Clinton — who has been campaigning on Obama’s legacy — criticized Sen. Bernie Sanders for writing a forward for a book focused on the ways that Obama’s administration has disappointed progressives.

“He wrote a forward for a book that basically argued voters should have buyers remorse when it comes to President Obama’s leadership and legacy, and I just couldn’t disagree more with those kinds of comments,” Clinton said, to loud applause. “The kind of criticism that we’ve heard from Senator Sanders about our president, I expect from Republicans. I do not expect it from someone running for the Democratic nomination to succeed President Obama.”

“Madam Secretary, that is a low blow,” Sanders responded. “I think it is really unfair to suggest that I have not been supportive of the president. I have been a strong ally with him on virtually every issue. Do senators have the right to disagree with the president? Have you ever disagreed with a president? I suspect you may have.”

Clinton shot back, saying that calling the president “weak” and a “disappointment” and suggesting that he should have a primary opponent in the 2012 election goes beyond “saying we have our disagreements.” Sanders was ready with a retort of his own: “Well, one of us ran against Barack Obama. I was not that candidate.”

Sanders has positioned himself somewhat apart from Obama’s presidency, saying that the entire system is in need of a revolution to disrupt the political status quo. Clinton’s campaign has repeatedly hit him on this point, arguing it’s unfair to suggest Obama has a “leadership gap.”

This particular dispute will likely come into play in the upcoming Democratic primary in South Carolina, where both candidates are vying for the African American vote. South Carolina voters are largely supportive of the president and may not respond well to a candidate who distances themselves from him.