While the campaign brandished the endorsement in ads across Facebook and Instagram, Warren herself didn’t mention it during either of her policy-heavy town halls in Eastern Iowa on Sunday. She was clearly excited about the news, busting a move when staff told her Saturday night.

And there was an uptick of energy at her events, including the final town hall of the weekend at a food-and-craft market in a developing part of this city. She was joined there by Jonathan Van Ness, one of the hosts of Netflix's “Queer Eye.”

“This moment in history is our time to choose courage over fear,” Warren told a standing-room-only crowd of around 900 people, according to an unverified estimate from her campaign. “This moment in history is our time to dream big and fight hard. This moment in history is our time to win!”

This weekend’s roughly 36-hour push by Warren — as much as the Senate schedule would permit — allowed her to fine-tune her closing argument, centered around her electability, gender, and an ideology-crossing focus on ridding Washington of “corruption.”

In recent weeks, Warren and her campaign have more explicitly tried to tackle the “electability” question as polls have showed Democrats are less convinced she can beat President Donald Trump in November. Surrogates have pitched her as the candidate who can best unite the party going into the general election because of her appeal to both Biden and Sanders voters.

Iowa voters are seeing another pitch on TV. “He fears Elizabeth Warren the most,” a recently deployed Iowa ad says of Trump, using an audio clip from MSNBC’s Lawrence O’Donnell. “I’m Elizabeth Warren, and I approve this message because I’m going to beat him.”

The backdrop behind her at the Cedar Rapids event spelled it out in plain English: “Win With Warren.”

Asked at a town hall here why uncommitted Democrats should caucus for her next week instead of Sanders or the other top candidates, she made a case for herself but declined to explicitly criticize the other candidates.

“Let me tell you why I think you should caucus for me: I know how to fight, and I know how to win,” Warren said. “In fact, I’m the only person in this race who has beaten an incumbent Republican anytime in the last 30 years.”

Electability questions have dogged Warren in part because some voters fear that a woman can’t beat Trump after Hillary Clinton’s 2016 loss. Warren is attempting to defuse that anxiety by focusing on her own electoral track record and the success of female candidates in the 2018 midterms.

“I just want to be clear: Women win,” Warren said. “I think that one of the questions for everyone is, ‘Ok, I hear it. But how can a woman beat Donald Trump?’ And the answer lies in what I’ve already talked to you about: This is the most corrupt administration in history. We’re going to beat Donald Trump by drawing that distinction.”

Asked by a reporter after Sunday’s event here why she is talking about gender and electability more, Warren said: “People ask the question.” She added: “It’s important to get it out there. This can’t be a hidden question people mask in different ways.”

The Des Moines Register’s endorsement, along with late support from local elected officials and activists here, are critical backing in a state where she has concentrated her efforts.

Warren has invested more time in Iowa than any other state: 55 days, compared to 32 in New Hampshire, 17 in South Carolina, and 12 in Nevada, according to the campaign’s own tally.

They also hired early and often, embedding organizers in Iowa communities months before rival campaigns. “There's no doubt about it — we're running the strongest organizing operation in the state, and our ground game is how we're going to win Iowa,” the campaign told supporters in a recent email.

As Warren has plateaued or slumped in the polls in recent weeks, however, the campaign has begun playing down expectations for an Iowa knockout victory and preparing supporters for a protracted fight for delegates through March and April.

“We expect this to be a long nomination fight and have built our campaign to sustain well past Super Tuesday and stay resilient no matter what breathless media narratives come when voting begins,” campaign manager Roger Lau wrote in a memo last week, pointing to the campaign hiring up robust field teams in later contests over the last several months. At over 1,000 full-time staffers, the campaign likely has the largest operation besides billionaire Mike Bloomberg, who is self-funding his campaign.

Historically, candidates who’ve earned the Register’s endorsement have seen a polling bounce in Iowa, according to the data journalism outlet FiveThirtyEight. But the Register bump hasn’t usually resulted in victory: From 1988 through 2012, the Register-endorsed candidate never went on to finish first in the caucuses, a streak that was broken by Hillary Clinton’s razor-thin victory in 2016.

Alex Thompson reported from Washington.