Good Tuesday morning, I'm Jake Sherman and welcome to your political playbook audio briefing.

Stay tuned after the show for a message from the National Retail Federation.

And I'm Anna Palmer. The Democratic Primer is set to enter a new phase tonight, 20 days before the first caucus,

with tenuous non-aggression packs breaking down and the president sharpening his attacks and focus on a field

that's finally been paired down to its top tier. The CNN-Demoyne-register debate tonight in

Des Moines happens with this backdrop. Elizabeth Warren and Bernie Sanders are warring, with the

Massachusetts Senators' allies and aides seemingly leaking damaging information about her colleague from Vermont.

Two prominent black leaders, Senators Corey Booker and Kamala Harris, are out of the field,

and Mike Bloomberg is pouring money into the contest, looming large on the sidelines and attracting

the president's ire and attention. That's not to mention Joe Biden versus the field.

The rest of the candidates are trying to gingerly make the case

that the former VP is out of step with the party's voters and of a different generation.

Biden, meanwhile, has proved a durable, if not dominant frontrunner.

It could be the most momentous debate yet. The war between Sanders and

Warren is hitting an absolute fever pitch sparked by a CNN report by M.J. Lee, which had Sanders

telling Warren a woman could not win the presidential race against Donald Trump. Sanders denies it,

but Warren is now on the record saying it's true. There's almost no chance that doesn't play a

role in tonight's contest. Meanwhile, as Sanders and Warren eat at each other, a super PAC that supports Biden is going up on the air with an ad touting the former vice president's experience on the world stage. The ad, paid for by Unite the country, says this. We need somebody in the Oval Office who understands the gravity and the consequences of

their decisions. Back on Capitol Hill, Burgess Everett and John Bresnehan have a must-read

story on Republicans facing an internal reckoning during the trial over impeachment witnesses.

They report Senator Susan Collins sent a letter to GOP leaders that they can't assume

should want to move as quickly through the

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