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DES MOINES, Iowa — If you want to know why Joe Biden is going (mostly) all-in here in Iowa, moving more of his advertising dollars into the Hawkeye State, look no further than our brand-new national NBC News/Wall Street Journal poll.

Bernie Sanders has jumped into the national lead among Democratic primary voters, albeit well within the margin of error — it’s Sanders 27 percent, Biden 26 percent, Elizabeth Warren 15 percent, Bloomberg 9 percent, Pete Buttigieg 7 percent and Amy Klobuchar 5 percent.

Sanders’ African-American support has increased (from 8 percent in December to 28 percent now — though still behind Biden’s 52 percent).

And he’s almost tied with Biden among non-white Democratic primary voters — 32 percent support for Sanders, 34 percent for Biden.

Bottom line: If Biden doesn’t stop Sanders in Iowa, there’s a real chance he might not be able to stop him after the first two states (and maybe Nevada, too).

And Iowa is ripe for a (slight) Biden upset.

Sanders’ rise could consolidate the anti-Bernie vote around Biden; the impeachment trial has kept Sanders and the other senators away from the campaign trail; and it doesn’t look like Klobuchar is going to reach the 15 percent threshold in most precincts, which could boost Biden’s post-realignment numbers.

Sure, South Carolina might be a firewall for Biden.

But if Iowa is still for the taking, this might be his best shot to stop a surging Sanders.

A structurally divided Democratic Party

All things considered, the Democratic candidates’ attacks on each other in the build-up to Iowa have been pretty mild — especially compared with the GOP race of 2016. (That includes Buttigieg’s light digs at Biden and Sanders yesterday.)

But our NBC/WSJ poll shows a very divided party when looking at the coalitions for the two Dem frontrunners.

Among those 18-34 (30 percent of the electorate): Sanders gets 47 percent, Warren 20 percent, Andrew Yang 9 percent and Biden 8 percent.

Among those 65-plus (22 percent): Biden 41 percent, Warren 14, percent, Bloomberg 14 percent and Sanders 10 percent.

Among liberals (52 percent): Sanders 32 percent, Warren 23 percent, Biden 21 percent.

Among moderates/conservatives (45 percent): Biden 33 percent, Sanders 19 percent, Bloomberg 12 percent.

And check out this divide: Biden voters have a 40 percent-to-23 percent positive view of capitalism, while Sanders voters have a 60 percent-to-4 percent positive view of socialism.

What do Democratic primary voters want?

Our NBC/WSJ poll also measures what Democratic primary voters are looking for in 2020.

Seventy-three percent say it’s very important to them — registering either a “9” or “10” on a 10-point scale – to vote for a Dem candidate who has the best chance of defeating Trump. (Among those 73 percent, the Dem ballot is: Biden 32 percent, Sanders 21 percent, Warren 16 percent.)

Fifty-eight percent say it’s very important to vote for a candidate who proposes large-scale policy changes. (Among those 58 percent, it’s Sanders 36 percent, Biden 24 percent, Warren 16 percent. It’s telling that Warren has dropped to third here.)

Twenty-seven percent say it’s very important to continue Barack Obama’s policies and agenda. (Among that 27 percent, it’s Biden 44 percent, Warren 15 percent, Bloomberg 13 percent and Sanders 12 percent).

And 21 percent say it’s very important to elect the first woman. (Among that 21 percent, it’s Biden 41 percent, Warren 27 percent and Sanders 16 percent.)

Lamar Alexander: Yeah, Trump did it — but don’t impeach him

That was essentially the statement that Sen. Lamar Alexander, R-Tenn., released last night in explaining why he’s against any witnesses in the Senate impeachment trial.

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Alexander said: “There is no need for more evidence to prove that the president asked Ukraine to investigate Joe Biden and his son, Hunter; he said this on television on October 3, 2019, and during his July 25, 2019, telephone call with the president of Ukraine. There is no need for more evidence to conclude that the president withheld United States aid, at least in part, to pressure Ukraine to investigate the Bidens; the House managers have proved this with what they call a ‘mountain of overwhelming evidence.’”

He continued, “The question then is not whether the president did it, but whether the United States Senate or the American people should decide what to do about what he did. I believe that the Constitution provides that the people should make that decision in the presidential election that begins in Iowa on Monday.”

In other words: Let the vote in November decide Trump’s fate.

But here’s the hole in that logic: If you caught someone trying to cheat in a game, is the best punishment to play another game? Or is it to not let that person play again?

What’s keeping that person from not trying to cheat again?

Tweet of the day

Romney on Trump ahead of impeachment verdict: "He won and I didn’t. On the other hand, he won and I didn’t but I would not have done what he’s done in order to win.” @MarkLeibovich on the only Republican who has vocally pushed for witnesses in the trial https://t.co/jBref25Lr5 — Julie Davis (@juliehdavis) January 31, 2020

You might not remember this, but former Congressman John Delaney, D-Md., was actually the first major Dem to announce running for president in 2020.

Back in July of 2017!

And today — three days before the Iowa caucuses — he announced he’s dropping out of the race.

“It has been a privilege to campaign for the Democratic nomination for President, but it is clear that God has a different purpose for me at this moment in time. I leave this race with a profound sense of gratitude to the voters who shared with me their hopes and concerns for our magnificent country, in admiration for the other contenders for the nomination and proud of the work we did to change the debate,” he said in a statement.

On the campaign trail today

The activity in the Hawkeye State with three days to go: Joe Biden hits Burlington, Fort Madison and Mount Pleasant… Pete Buttigieg holds town halls in Sioux City, Council Bluffs, Clinton and Davenport… Rep. Pramila Jayapal, Rep. Ilhan Omar, Rep. Rashida Tlaib and Jane Sanders stump for Bernie Sanders… Reps. Katie Porter and Ayanna Pressley campaign for Elizabeth Warren… Andrew Yang is in Tipton, Monticello, Grundy Center Mason City and Decorah… And Tom Steyer travels to Clinton and Dubuque.

Dispatches from NBC’s campaign embeds

As the days until the Iowa caucuses wind down, most of the candidates are trying to rev up their closing messages. NBC’s Ben Pu reports that Andrew Yang is also having a heartfelt, emotional closing to his time in Iowa. Per Pu, while on his 13th day of his last bus tour in Iowa, Pu got emotional as he reminisced about his time in the Hawkeye State. “I've been coming to Iowa for almost two years. I started coming in spring of 2018, I have to say I loved campaigning here, you all have been beautiful to me and my family. My kids love it here, they came in the summer, they've been here this past week. One, they love daddy's boss ‘cause now daddy's got a huge boss. Don't know if you saw it. My boys don't really understand what I'm doing. I just told them daddy has a really big deadline on Monday,” Yang said. “But I have to say I love Iowa. Campaigning here the last two years has been the journey of my life. I'm really glad that you all are going to determine the future of our country.”

And while Iowa is just a few days away, some campaigns are starting to slowly shift their focus to New Hampshire. NBC’s Amanda Golden reports that Amy Klobuchar is holding her first tele-town hall with Granite Staters this morning — as long as impeachment doesn’t get in the way. The town hall should begin at 10:15 a.m., but as every senator running for president has learned, that schedule is “subject to change.”

Data Download: The number of the day is … 59 percent

59 percent.

That’s how many Democratic primary voters say they have seen an ad from Michael Bloomberg on TV or social media, according to our new NBC/WSJ poll.

That’s more than double the share that have seen ads from the race’s two national frontrunners, Bernie Sanders (28 percent have seen his ads) and Joe Biden (25 percent.)

Bloomberg has already spent more than $230 million on the airwaves so far, according to Advertising Analytics.

For Tom Steyer, who has also spent more than $100 million from his own pocket on TV advertisements so far, 33 percent of Democratic primary voters say they’ve seen a spot promoting him.

The Lid: Parachute Pants

Don’t miss the pod from yesterday, when we gave a glimpse into what it’s like to watch the national press corps descend on Iowa a few days before the caucus.

ICYMI: News clips you shouldn’t miss

A new video appears to show more evidence of Trump interacting with Lev Parnas.

What would happen to Iowa’s economy if the caucuses were no more?

Biden argued against trial witnesses in the 1999 impeachment debate.

A coalition of progressive groups are teaming up to fight back against anti-Sanders messaging.

It’s happening: Britain is withdrawing from the European Union today.

Trump Agenda: Lamar Alexander vs. Howard Baker

Here’s our team’s full write-up of Lamar Alexander’s decision to vote no on further Senate trial witnesses.

What if there’s a tie when the Senate votes?

Hm, this isn’t good news for backers of Trump’s border wall.

The president’s team is working on his State of the Union — and avoiding a focus on the impeachment debate.

2020: Biden’s closing message

Here’s what Joe Biden’s closing argument in Iowa sounds like.

And here’s what Donald Trump sounded like in Des Moines last night.

Democrats who oppose abortion rights are finding it harder and harder to stay in the party.