Warren Told Sanders After Debate, ‘I Think You Called Me a Liar on National TV’

DES MOINES — The nonaggression pact between the Democratic presidential campaign’s two leading liberals blew up on the debate stage Tuesday night, with Senator Elizabeth Warren accusing Senator Bernie Sanders after the event of calling her “a liar on national TV.”

The tense remarks represent a startling break between Ms. Warren and Mr. Sanders, who had often been united against the campaign’s leading moderates, former Vice President Joseph R. Biden Jr. and former Mayor Pete Buttigieg of South Bend, Ind.

“I think you called me a liar on national TV,” Ms. Warren told Mr. Sanders, referring to their dispute at the debate over whether he told her in a private 2018 meeting that a woman could not be president. The New York Times described details of their exchanges on Wednesday afternoon, and CNN broadcast an audio recording on Wednesday night.

According to the new audio, Mr. Sanders responded, “What?”

“I think you called me a liar on national TV,” she said again.

“You know, let’s not do it right now,” he said. “If you want to have that discussion, we’ll have that discussion.”

Ms. Warren replied, “Anytime.”

“You called me a liar,” Mr. Sanders said. “You told me — all right, let’s not do it now.”Tom Steyer, the billionaire businessman, approached Mr. Sanders in the middle of his exchange with Ms. Warren.

“I don’t want to get in the middle,” Mr. Steyer said. “I just want to say, ‘Hi, Bernie.’”

The newly exposed rift threatens to shake up an unsettled race that has the four leading candidates in an effective tie less than three weeks before the first-in-the-nation Iowa caucuses, a contest for the affection of Democrats who have a long history of recoiling from the sort of negative personal attacks in full view of a national audience.

It has already roiled progressives, who fear the public division will benefit the moderates in the race — and, more broadly, threatens the movement they have tried so hard to build.

Both the Warren and Sanders campaigns declined to comment on Wednesday. By the time CNN aired the footage, the two candidates had not spoken about the exchange, people familiar with their whereabouts said, though they are expected to be in close contact when the Senate convenes Friday.

CNN executives initially said they did not believe the exchange had been captured by the network’s microphones. The network said its journalists located a recording late on Wednesday after reviewing audio from the microphones that Mr. Sanders and Ms. Warren had been wearing onstage.

Over the weekend, Ms. Warren said she was “disappointed” in Mr. Sanders after Politico reported that his campaign had distributed a script to volunteers suggesting she appealed mainly to highly educated voters. On Monday, CNN reported that Mr. Sanders had told Ms. Warren in a private meeting in 2018 that he thought a woman could not win the presidency; Mr. Sanders vehemently denied it.

“I thought a woman could win; he disagreed,” Ms. Warren said in a statement on Monday.

On Tuesday, the issue burst forth onto the debate stage in a remarkable moment before a national audience that captured the recent friction between the two senators.

“I didn’t say it,” Mr. Sanders insisted, about her characterization of his 2018 remarks. Ms. Warren disputed that, then called him her friend before pivoting to make the case that of the six candidates onstage, only the women had won all of their elections.

After the debate, Mr. Steyer repeatedly insisted he did not hear the back-and-forth between the two liberals.

“I was just saying good night to the two of them,” he said during a brief exchange with reporters in the debate spin room at Drake University. “I didn’t hear anything.”

Michael M. Grynbaum and Astead W. Herndon contributed reporting from New York.