Vermont Sen. Bernie Sanders (I) is strongly denying a CNN report alleging that he told Sen. Elizabeth Warren (D-Mass.) that a woman cannot win the White House.

CNN reported Monday that the remark came during a meeting in Warren's apartment in late 2018 during which the candidates discussed their presidential ambitions. Warren told Sanders she would "make a robust argument about the economy and earn broad support from female voters," and Sanders responded he did not believe a woman could win the presidency, according to CNN.

It has previously been reported that the two agreed in that meeting that they would not attack each other as rivals for the Democratic nomination.

In a statement to CNN Monday, Sanders called the report "ludicrous."

"It is ludicrous to believe that at the same meeting where Elizabeth Warren told me she was going to run for president, I would tell her that a woman couldn't win," Sanders said.

"It's sad that, three weeks before the Iowa caucus and a year after that private conversation, staff who weren't in the room are lying about what happened. What I did say that night was that Donald Trump is a sexist, a racist and a liar who would weaponize whatever he could. Do I believe a woman can win in 2020? Of course! After all, Hillary Clinton beat Donald Trump by 3 million votes in 2016."

CNN cited four sources in the report - two people who are said to have spoken with Warren directly after the meeting and two others said to be "familiar with the meeting."

The Hill has reached out to both the Sanders and Warren campaigns for comment. Warren's campaign declined to comment to CNN.

Sanders's online supporters are furious over the allegations, viewing it as a desperate attempt by the media and Warren staffers to blunt his momentum in the race.

The CNN report comes amid growing tensions between Sanders and Warren, with polls finding the progressives locked in a tight race for the nomination with the Iowa caucuses only weeks away.

On Sunday, Warren ripped Sanders over a Politico report alleging that his campaign quietly instructed volunteers to tell voters that Warren would be a weak general election candidate because her appeal is limited to "highly-educated, more affluent people who are going to show up and vote Democratic no matter what."

According to the talking points, the volunteers were instructed to tell voters that Warren is "bringing no new bases into the Democratic Party."

Warren fired back directly at Sanders, saying she was "disappointed to hear that Bernie is sending his volunteers out to trash me."

"Bernie knows me and has known me for a long time," Warren said. "He knows who I am, where I come from, what I have worked on and fought for and the coalition and grassroots movement we are trying to build. Democrats want to win in 2020 we all saw the impact of the factionalism in 2016 and we can't have a repeat of that."

"I hope Bernie reconsiders and turns his campaign in a different direction," Warren added.

Sanders sought to distance himself from the report.

"We have over 500 people on our campaign," he said. "People do certain things. I'm sure that on Elizabeth's campaign people do certain things as well."

"But you've heard me for months, I have never said a negative word about Elizabeth Warren, who is a friend of mine. We have differences on issues. That's what a campaign is about."