First Read is your briefing from "Meet the Press" and the NBC Political Unit on the day's most important political stories and why they matter.
WASHINGTON — When the fieriest moment at last night's Democratic presidential debate was that Ron Reagan Jr. TV commercial ("Ron Reagan, life-long atheist, not afraid of burning in hell"), you know it was a relatively tame debate.
Still, what was new was the anticipated clash between Bernie Sanders and Elizabeth Warren over gender politics — as well as the fact that Warren appeared to reject Sanders' handshake after the debate.
(If you're promising to be the unity candidate, like Warren and her supporters have done, you have to accept that handshake, right?)
CNN's Abby Phillip: "Senator Sanders, CNN reported yesterday that — and Senator Sanders, Senator Warren confirmed in a statement, that in 2018 you told her that you did not believe that a woman could win the election. Why did you say that?"
Sanders: "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 knows me knows that it's incomprehensible that I would think that a woman cannot be president of the United States."
Phillip: "Senator Sanders, I do want to be clear here, you're saying that you never told Senator Warren that a woman could not win the election?"
Sanders: "That is correct."
Phillip: "Senator Warren, what did you think when Senator Sanders told you a woman could not win the election?"
Warren: "I disagreed. 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 I think the best way to talk about who can win is by looking at people's winning record. So, can a woman beat Donald Trump? Look at the men on this stage. Collectively, they have lost 10 elections. The only people on this stage who have won every single election that they've been in are the women."
Besides that exchange, however, there weren't many fireworks. And we have a theory as to why.
With the Iowa caucuses less than three weeks away, the candidates all realize that Iowa Democrats are all that matter right now.
And Iowans typically don't reward negative campaigning.
Data Download: The number of the day is … 19 minutes and 11 seconds
19 minutes and 11 seconds.
That's how long Elizabeth Warren spoke during last night's debate, according to NBCNews.com's tracker. Warren spoke the most of any candidate, while Bernie Sanders spoke the second longest — 18 minutes and 26 seconds.
Second-to-last and more than only last-minute debate participant Tom Steyer? That would be Joe Biden, who has consistently been at or near the top of Democratic polls, but who spoke for just 16 minutes and 17 seconds.
Tweet of the day
The Lev Parnas documents
One of the truisms of the entire Ukraine scandal is that the more we learn, the worse the story looks for President Trump and his allies.
"New materials released by House Democrats appear to show Ukraine's top prosecutor offering an associate of President Trump's personal attorney, Rudolph W. Giuliani, damaging information related to former vice president Joe Biden if the Trump administration recalled the U.S. ambassador to Ukraine," the Washington Post writes.
"The text messages and documents provided to Congress by former Giuliani associate Lev Parnas also show that before the ambassador, Marie Yovanovitch, was removed from her post, a Parnas associate now running for Congress sent menacing text messages suggesting that he had Yovanovitch under surveillance in Ukraine. A lawyer for Yovanovitch said Tuesday that the episode should be investigated."
It's all a reminder that Democrats benefit when the impeachment storyline turns to the substance, and Republicans benefit when it's about process.
Our question: In retrospect, did House Democrats make a mistake in wrapping up their impeachment inquiry so quickly, before we even learned of these Parnas documents?
2020 Vision: Things are getting interesting in the Kansas Senate race
"Rival Kansas Senate candidates Kris Kobach and Rep. Roger Marshall have talked to President Donald Trump, with Marshall looking to boost his chances of defeating Trump's earliest prominent supporter in the state," the AP writes.
On the campaign trail today
A few of the candidates remain in Iowa after last night's debate: Biden makes a local stop in Des Moines before heading to Dallas… Pete Buttigieg holds town halls in Newton, Cedar Falls and Mason City… And elsewhere, Tulsi Gabbard stumps in New Hampshire.
Dispatches from NBC's campaign embeds
NBC's Maura Barrett and Priscilla Thompson report from the spin room after the Democratic debate: "Julian Castro, now in the role of surrogate to Elizabeth Warren rather than that of candidate, wavered when asked if he still believed Iowa should not go first in the Democratic nominating contest. 'I had a good conversation with Tom Perez after I decided to end my campaign, and I said that after this 2020 cycle I hope that the DNC will take a look at a number of things; the debate thresholds, how we do the nominating contest,' Castro said. He did, however, tout Warren's being the 'only' candidate on stage to defeat an incumbent Republican in the last 30 years.' Some context, 30 years ago, in 1990, Bernie Sanders won his first election against an incumbent Republican."
And Pete Buttigieg surrogate, Rep. Deborah Berry, tried to downplay fears that Pete Buttigieg still doesn't have much support from the black community, saying in the spin room, 'I remember when Barack Obama came out and he made his announcement. I was like, who is this guy and I wasn't behind him. I didn't support him because I didn't know him. But then as I begin to listen and hear his messages and the words he was saying and all about hope you know the future. I said, this man is saying something. And that's what I think people just need to hear Mayor Pete and hear his message of unity and uniting all of us.'"
NBC's Gary Grumbach reports from Bernie Sanders world that the campaign is saying the debate day was "the best single day for fundraising on a debate day for the entire campaign." Grumbach reports, per the campaign, Sanders raked in $1.7 million from more than 100,000 contributions.
The Lid: Wild-n-crazy Tuesday night
Don't miss the pod from yesterday, when we previewed the debate.
ICYMI: News clips you shouldn't miss
New documents show that Rudy Giuliani sought a private meeting with the Ukrainian president — and that former ambassador Marie Yovanovitch appears to have been closely monitored by a Trump donor and congressional candidate.
Michael Flynn is withdrawing his guilty plea.
Trump weighed in on the question of whether Bernie Sanders told Elizabeth Warren that a woman can't win the presidency.
Trump Agenda: Gutting water protections
The Trump administration is taking new aim at protections for the country's wetlands and streams.
Here's the latest on the Trump tax returns case.
The Supreme Court may toss out the convictions in the Bridgegate case.
2020: "Painfully dull"
POLITICO calls last night's debate "painfully dull."
Michael Avenatti was arrested again.