Sanders and Warren split with three weeks until Iowa caucuses

The long-anticipated Elizabeth Warren vs. Bernie Sanders fight has arrived.

Driving the news: CNN reported today, "Bernie Sanders told Elizabeth Warren in [a] private 2018 meeting that a woman can't win." Politico reported on Saturday, "Sanders’ campaign has begun stealthily attacking Warren as a candidate of the upper crust who could not expand the Democratic base in a general election."

Why it matters: Iowa Democrats caucus in less than a month, and you can expect this budding feud to pop up at tomorrow night's debate.

The big picture: The two are competing to unify the far-left flank of the party.

• After New Hampshire in February comes a map friendlier to Joe Biden and mountains of spending by Michael Bloomberg and Tom Steyer.

Between the lines: The most important line in the CNN story is that Warren’s campaign declined to comment, notes Axios' Jonathan Swan.

• Warren was in the room for Sanders' alleged comment — and, by not commenting, she allows the story to run.
• ⚡"Elizabeth Warren recalled an explosive account of a meeting with Bernie Sanders in which he said he didn’t believe a woman could win in 2020," BuzzFeed reports.
• The other side: Sanders denied saying this to Warren and blamed the story on "staff who weren't in the room [who] are lying about what happened."

The bottom line: Time spent fighting each other is time the campaigns won't spend going after Biden.

Go deeper: Warren says she's "disappointed" to be targeted by Sanders campaign