DES MOINES — A year ago, then-South Bend Mayor Pete Buttigieg took his first trip to Iowa as a presidential candidate. He had barely any staff, so he piled in a car with his husband and a couple of early hires to drive the 400 miles west.

Now, with just weeks until the caucuses, Buttigieg’s Iowa staff numbers in the hundreds, along with scores of volunteers eager to knock on doors and phone-bank. He regularly draws big crowds. And his fundraising haul has enabled him to blanket the state with TV ads touting him as the candidate who can bring the country together after President Trump.

Still, it is far from clear he will be able to turn his momentum into a win on caucus night. A recent Des Moines Register poll showed Buttigieg in a near-tie with former vice president Joe Biden and Sens. Bernie Sanders (I-Vt.) and Elizabeth Warren (D-Mass.). Voters — even those who like him — are worried about his inexperience, electability and struggles with black voters.

With the Iowa caucuses and New Hampshire primary approaching, an international crisis gave the race for the democratic presidential nomination a new urgency. (The Washington Post)

In this unusually fluid race, with a high number of undecided voters, Buttigieg acknowledges that he needs an Iowa win to prove he can win nationally. Foreign policy has abruptly vaulted to the forefront of voters’ concerns, and Buttigieg has less of a clear fallback than some of his rivals should he stumble in the caucuses.

“Iowa is very important because it’s our opportunity to demonstrate our strength to a lot of voters I think are very pragmatic — in places like South Carolina and Nevada — who above all want to see a candidate who can win,” Buttigieg said Saturday in Las Vegas.

To try to bring home a victory, Buttigieg is sweeping across Iowa this week, making at least 12 town-hall stops, including 10 in counties Trump carried in 2016. The campaign prioritized red and purple counties in two trips through Iowa in late December, too.

To understand how Pete Buttigieg became a presidential contender, you have to start in South Bend, Ind. (The Washington Post)

It is part of his strategy to pitch himself as a moderate who would not alienate conservatives, even as he argues his proposals would make him the most progressive president in recent memory.

The message he has delivered in Iowa lately makes clear overtures to disgruntled Republicans — or what he calls “future former Republicans” — whom he argues he can attract. He suggests he will be able to build bipartisan consensus. And he, more than any candidate in the field, suggests that Republicans have co-opted faith, arguing that religious Americans can find a like-minded leader in him.

There are signs that moderates are responding to that message. Longtime Iowa Democratic Party activist Terri Hale, who endorsed Buttigieg last summer and calls him “a realistic progressive,” recently planned a small meet-and-greet for Buttigieg at her home near Des Moines.

She invited only undecided and Republican acquaintances, to try to sell them on her candidate. “We ended up having to move it to a bigger place because we had about 170 people,” Hale said. “Not everybody there was an undecided or Republican, but I know a few Republicans for sure who are going to caucus for Democrats because of Pete who were there.”

The campaign is also doubling down on its robust organizing operation in the final weeks before the vote. Though Buttigieg started far behind his Democratic rivals in building a ground game — waiting until around Labor Day to begin opening field offices — he has now assembled one of the largest operations in the state.

According to several Democratic county chairs, Buttigieg’s operation is second only to Warren’s. “When you see a Warren organizer, a Buttigieg organizer usually isn’t far behind,” said one Democratic county chair, who spoke on the condition of anonymity to give a candid assessment of the race.

But that may not be enough. In recent weeks, some county chairs have sensed shifting feelings about Buttigieg.

Voters who had been leaning toward or even committed to him have reported new anxiety, raising questions about his age, his lack of Washington experience and his struggle to win over minority voters.

“I honestly think he peaked a little bit too early, unfortunately, and people are kind of having buyer’s remorse,” the Democratic county chair said of Buttigieg. “The second-guessing is starting. I think a big part of it is foreign policy, which is now becoming a huge issue in this election, which none of us expected. And that does play to Joe Biden’s strength, and in many ways they are in the same lane.”

While Buttigieg seemed to benefit in the fall from heavy spending on television, he has lost that advantage. In recent weeks, his ads have been matched almost one-to-one by Biden spots, including a new ad emphasizing Biden’s foreign policy experience against the backdrop of recent tensions with Iran.

Interviews with undecided voters at candidate events in recent days suggest there is still a lot of goodwill for Buttigieg and that he remains in consideration. But many still are not convinced.

“He’s too young,” said Lynn Muhs, 67, an undecided voter from Newton, Iowa. She spoke after attending a Sanders rally Saturday as part an effort to see all the candidates in person before making a final decision on whom to support.

She praised Buttigieg as a “good talker, a good speaker,” but she worried about his lack of Washington experience. In the past, she said, she thought an outsider might have been good. But she looks at that question differently considering Trump. Whoever follows Trump, she said, needs to be able to restore order.

“I could imagine him as someone who could win later down the road, but . . . he doesn’t have the background and he doesn’t have the experience, not in federal government anyway,” Muhs said. “Being a small-town mayor, I mean, even if he were a large-town mayor, to me that is still not the same thing. You need that experience.”

To combat those worries, Buttigieg and his team are encouraging their volunteers to reach out to their friends and neighbors. The campaign flew its national caucus director, Travis Brock, to conduct some trainings in person. Buttigieg organizers are teaching precinct captains how to build “empathetic bridges” to supporters of other campaigns in the hopes of bolstering their ranks on caucus night.

At a recent precinct captain training in Ankeny, north of Des Moines, a Buttigieg staffer reminded the 90 people gathered not to take an Iowa win for granted. One slide from a PowerPoint presentation showed a list of polls from this point in the 2004 Democratic election, when Howard Dean was leading. John F. Kerry went on to win Iowa, a surprise comeback that helped him clinch the Democratic presidential nomination.

“They were dating Howard Dean, and they married John Kerry,” Shannon Sankey, a Buttigieg organizer overseeing Ankeny, told the group. The race now, she said, is just as fluid. “The polls are always lying to us,” she said. “You never want to believe a poll, because it’s always changing.”

Around the room, volunteers, many wearing navy-and-gold Buttigieg campaign pins, grew serious. Their game faces were on.

“We’re focusing on persuasion and mobilization,” said Matt McCoy, a former state senator and early Buttigieg endorser who is involved in Buttigieg’s Iowa “kitchen cabinet,” a regular strategy meeting of staffers and other campaign members.

McCoy said the campaign still sees plenty of time to change minds. His preferred candidate agrees.

“What we’re seeing is everything from voters who have been coming out to events for a year and are narrowing down their choices to people who are just now tuning in,” Buttigieg said Saturday. “The message won’t change, because my values haven’t changed. But you will see us continuing to build toward a closing argument that really brings home why I’m the best nominee to defeat Donald Trump and why I’d be the best president.”