The Warren-Sanders feud just got way uglier

That's the only possible takeaway from the ongoing back and forth between Sens. Bernie Sanders of Vermont and Elizabeth Warren of Massachusetts over whether the former told the latter that he did not believe a woman could be elected president in 2020. And the feud got worse, not better, during -- and after -- Tuesday night's Iowa debate.

Asked directly about Warren's statement that Sanders had told her in a December 2018 meeting that he didn't believe a woman could win, the Vermont senator said this:

"Well, as a matter of fact, I didn't say it. And I don't want to waste a whole lot of time on this, because this is what Donald Trump and maybe some of the media want. Anybody who knows me knows that it's incomprehensible that I would think that a woman cannot be President of the United States."

Warren was then asked what her reaction was to what Sanders had said back in 2018. "I disagreed," she said. "Bernie is my friend, and I am not here to try to fight with Bernie. But, look, this question about whether or not a woman can be president has been raised, and it's time for us to attack it head-on."

And that was it -- until the end of the debate. Sanders and Warren approached one another and he stuck out his hand. She did not shake it. What followed was a brief but clearly uncomfortable conversation. As Sanders' campaign co-chair Nina Turner put it on CNN: "I'm not sure what she said, but you can read the body language. Obviously, their conversation was not pleasant."

Uh, yeah. Watch it for yourself.

Then the fight turned to social media. As of Wednesday morning, the hashtag "#neverWarren" was trending as Bernie allies took to Twitter to attack the Massachusetts senator as a lying snake. (Not kidding; snake emojis were everywhere in the anti-Warren tweets.) "Lie or mischaracterize your 'friend's' comments, double down, refuse to shake his hand," tweeted Kyle Kulinski, a prominent liberal and YouTube host. "Are you watching America?" tweeted liberal activist and Sanders supporter Shaun King: "When @BernieSanders beat a Republican to win his congressional seat 29 years ago, Elizabeth Warren was still a Republican. One reason she never lost to a Republican is that she was a Republican for the first 47 years of her life."

On the other side of the argument, Third Way senior vice president Lanae Erickson tweeted this of the Sanders-Warren handshake-that-wasn't: "That moment when the dude who called himself a "feminist" on his profile shows his true colors on date 5...You hate to see it."

There are real consequences to all of these raw feelings. Sanders and Warren are the two most prominent liberals in the race, and for either one of them to beat former Vice President Joe Biden for the Democratic nomination this year, they will need the near-united support of the left. Up until a few days ago, that seemed like a very real possibility, with Warren and Sanders refusing to attack one another and their supporters -- online and off -- largely aiming their rhetorical fire at the likes of Biden and former South Bend, Indiana, Mayor Pete Buttigieg.

After Tuesday night, however, the idea of the Sanders people rallying around Warren if, after the first few primaries and caucuses, she looks like the most viable liberal candidate, now seems fanciful. And, vice versa for the Warren people being cool with the idea of Sanders as the liberal choice for 2020.

And that is true no matter what the two principals say (or don't say) about that now-famous December 2018 meeting and/or the no-handshake moment in Tuesday night's debate. What happened Tuesday night seems likely to reverberate not just through the Iowa caucuses in 19 days' time but the broader fight over who emerges as the liberal choice and whether -- or not -- the left is willing to rally around that person.