And after sources that had spoken to Warren told CNN about her recollection of Sanders doubting a woman could beat President Donald Trump in the 2020 election, Sanders issued a statement refuting the assertion.
Sanders disputed Warren's claim that Sanders made those comments.
Eighteen liberal advocacy groups are banding together to call for unity and try to rally against candidates supported by the "corporate wing" amid the recent spat between Sen. "We're fully conscious that the quest for the nomination is a zero-sum game and that individual voters will have to make a choice between these candidates".
We already know how this kind of destructive drama can end, don't we?
The exchange was interrupted by fellow candidate and environmentalist Tom Steyer, who said, "I don't want to get in the middle of it" and greeted Mr Sanders as the senator walked away.
Sanders allies feel betrayed by what they view as a low blow over an old misunderstanding.
Sanders, a longtime antiwar advocate who voted against the 2002 authorisation of war in Iraq, criticised Biden for supporting the war and said they heard the same arguments from officials in former President George W Bush's administration before coming to different conclusions.
Bernie Sanders and Elizabeth Warren embrace after the Democratic presidential debate at the Fox Theatre on July 30, 2019 in Detroit, Michigan.
Sanders first responded to Warren, who approached him after she shook hands with other candidates on stage after the debate concluded, saying that he didn't want to have "that discussion" at the moment. What stopped her becoming president was not Americans' refusal to vote for a woman, but the vagaries of the U.S. electoral college, which requires candidates to win a majority of states not votes.
"This isn't great", one Sanders ally said. "I'm disappointed by the turn of events, and that's an understatement". She then pivoted to touting the election viability of herself and Sen. Bee added that it's not insane to say that "America couldn't elect a woman president", as she "might have shouted it into a bottle of wine or 10 herself". His online supporters - the so-called Bernie Bros - have been accused of sexist attacks against rivals, critics and reporters.
Following the debate, progressive activists anxious that escalating tension between Warren and Sanders could divide liberals.
Tensions between Warren and Sanders' campaigns have been rising in the final weeks before voting.
Warren said he had told her a woman could not defeat Trump, adding that "I disagreed".
"I thought they were lying, I did not believe them for a moment", Sanders said.
"Well, as a matter of fact, I didn't say it", Sanders replied. Amy Klobuchar rounded out the top five with 10%. Warren said he did. Anyone so precious that they're threatening to sit out the election if their candidate doesn't get the nomination - or worse, vote for Trump - is choosing cult of personality over country. "They had a long conversation about the challenges a woman would face facing Trump, because she asked".
But there are enormous risks for Warren, who can not afford to alienate Sanders's liberal coalition. After the story was published, Warren repeated the accusations herself. And that is what we need to focus on. Bernie Sanders (I-VT) to accuse him of calling her a "liar" on national television.
Democratic strategist Eddie Vale said it's better for both campaigns to move on.