There’s two reasons why I think Bernie’s lying about whether he told Warren he did not think a woman could beat Trump.
Let’s set the stage: Bernie meets with his friend Warren at her D.C. apartment in December 2018 because they are both contemplating a run for the Presidency, and they both know they occupy exactly the same lane. As Warren put it: "Bernie knows me, and has known me for a long time. He knows who I am, where I come from, what I have worked on and fought for, and the coalition and grassroots movement we're trying to build." The two both want to further the progressive movement, and the purpose of their meeting is to explore how best to ensure that they don’t do anything which hurts the progressive movement.
Many have missed this, but the real purpose of the meeting was for Warren and Bernie to see if either could convince the other not to run.
Which brings me to the first reason we know Bernie is lying. Bernie believes in the Progressive movement and its values. And Bernie knows that a younger Progressive woman winning the Presidency would be better for Progressive values than yet another old white man winning, no matter that he too is a Progressive.
Which is why Warren’s pitch to Bernie to stay out of the race was that she could lay out the Progressive argument regarding the economy as well as he, but that she also could motivate female voters to vote for her.
Warren’s argument is a convincing one. Yet, Bernie did not bow out of the race. The question not being asked on this site is: Why didn’t Bernie bow out?
The only logical answer is because Bernie believed that Warren running as the Democratic candidate would be worse for the Progressive movement than him running as the candidate. And given that Bernie fully understands the value that a woman becoming President would have to the Progressive movement, he must have concluded that Warren couldn’t win. (The only other alternative is that for Bernie it is not about promoting Progressive values, just promoting himself.)
And, if Bernie did not think Warren could win, there are only two things he could have said to her: Either (1) a woman can’t beat Donald Trump or (2) you (Warren) can’t beat Donald Trump.
Even if he believed Warren was a flawed candidate who could not win, it is likely he chose to tell Warren that he didn’t think any woman could beat Trump, not just her. Why? Because Bernie was trying to convince Warren not to run, and it is a more convincing to make an argument that is not a personal attack on Warren only.
Sanders has basically admitted this: "I have never said a negative word about Elizabeth Warren, who is a friend of mine," Sanders said.
In short, given the purpose of the meeting, and what Bernie and Warren were trying to accomplish in that meeting, it seems obvious that Bernie said exactly what Warren claims — that he did not believe a woman could beat Donald Trump - in his effort to get her to step aside. (Obviously, this is not a statement that he’d want to admit to publicly — especially if his real view was that Warren couldn’t win because of her own personal flaws).
Second, Bernie’s statements to Warren at the debate are consistent with the conclusion that he’s lying when he denies saying that a woman could not beat Trump. Look at the transcript:
Warren: "I think you called me a liar on national TV.”
Sanders: "What?"
Warren: "I think you called me a liar on national TV.”
Sanders: "You know, let's not do it right now. If you want to have that discussion, we'll have that discussion."
Warren: "Anytime."
Sanders: "You called me a liar. You told me -- all right, let's not do it now."
Sanders doesn’t deny, to Warren’s face, that he said what she claims. Instead, he takes the weak approach of asking for time to explain somewhere in private. What he wants to explain we don’t know. (Perhaps he’s going to explain to her that he thinks she’s a flawed candidate, but chose to spare her feelings by making his objection based on all women.) And, then, when she says “anytime,” reinforcing that she knows he lied and so does he, Sanders loses it. He accuses her of calling him a liar — when and where we don’t know. But, that’s the act of someone trying to drag their opponent down to their level. The act of a person who lied, and who’s defense is “you lied also!”
Warren, in contrast, has consistently made blunt statements regarding what Bernie said back in December 2018: "I thought a woman could win; he disagreed," Warren said in the statement. She has absolute conviction he made the statement — which is why she refused to shake her friend’s hand. In a battle of witness credibility, a jury would believe Warren before Bernie.
And that’s what makes the most sense.
Having said al that, perhaps his lie was not improperly motivated. Perhaps given my reasoing it was a white lie. I’ll let others make that argument. But a lie it was.