DUBUQUE, Iowa - There were cars with Kamala Harris bumper stickers in the parking lot and, inside, a crowd of about 250 that grew so quickly staffers scrambled to add more chairs.

By the time Sen. Amy Klobuchar took the stage inside a convention room overlooking the Mississippi River here, it was standing room only - just as it had been during other stops in recent days as the senator from Minnesota crisscrossed the state. It was a welcome sign for a Democratic presidential candidate who has often struggled to attract the same kind of energy as her rivals.

For months, the same four candidates have been at the top of the polls here in this key early voting state: former vice president Joe Biden, South Bend, Ind., Mayor Pete Buttigieg, and Sens. Bernie Sanders, I-Vt., and Elizabeth Warren, D-Mass. But as Buttigieg faces more scrutiny and Biden struggles to generate enthusiasm, Klobuchar, a Midwestern centrist with a message of experience and electability, is attracting Iowans desperate to defeat President Donald Trump. Her challenge is persuading them she has a shot at winning, an upward climb for the candidate.

She's attracted increasingly large crowds in recent weeks - particularly in small towns that haven't gotten as much love from other candidates and where many Democrats say they are still undecided.

Around the state, Democratic party chairs have reported hearing more interest in her. And though she was at 6 percent support in the latest Des Moines Register-CNN-Mediacom poll of likely caucus-goers - a distant fifth place - the poll found that 39 percent of likely caucus-goers were still actively considering her, a number she and her staff have seized on as proof there is space for her campaign to grow.

"If I had to make a bet on the candidate most likely to have a late breakout into the top tier in Iowa, it would be Amy," said Peter Leo, chairman of the Carroll County Democrats in northwestern Iowa, who recently endorsed Warren in the race.

Klobuchar is trying to capitalize on that attention. In the past two weeks, she has doubled her number of field offices to 20, with the possibility of more expansion. She has about 60 staffers on the ground, up from 40 in late August but about half the number reported by Warren, Biden and Buttigieg. Still, she has made key hires, including Norm Sterzenbach, a former Iowa Democratic Party executive director and expert on caucus turnout who previously worked for former Rep. Beto O'Rourke's campaign.

Klobuchar's rise comes as moderate Democrats have reasserted their power in a presidential race that for months was dominated by sweeping liberal ideas, including Sanders's call for a political revolution and Warren's pitch for big, structural change. Democratic party leaders and voters here have openly worried expensive policies like Medicare-for-all could prove to be too polarizing and lead to Trump's reelection next year.

Klobuchar has made the same unwavering argument for months on the campaign trail, describing Medicare-for-all as a "pipe dream" and criticizing proposals like free college as something the nation can't afford. She has criticized other Democrats in the 2020 race, arguing that their liberal policies will doom them in the general. She presents herself, in contrast, as a political realist and, during her stump speech, often ticks through a litany of bills she has passed as a member of the Senate, many with the support of Republicans.

"What I do is I find common ground where I can find it. And then I stand my ground where I must," she said in Chariton.

She has also used her background as a moderate senator from the Upper Midwest to argue that she can appeal to Trump voters,a particular obsession of voters here.

In Dubuque, Klobuchar spoke in a room just down the hall where Trump made one of his earliest campaign appearances in Iowa. That 2015 rally attracted some 3,000 people, who laughed and cheered at a rambling speech where the candidate railed on Mexico, China and even Elton John.

While local Democrats have reported high enthusiasm leading up to the caucuses, some have pointed to that rally, one of the largest in the city's history, questioning if anyone in the party's 2020 field genuinely has the ability to win back those voters who backed Trump three years ago.

Klobuchar highlighted her background as a pragmatic lawmaker willing to cross party lines, saying it made her a "perfect match for Donald Trump." She was unsparing in her critique of the president, calling him a "whiner" for his recent decision to leave a NATO conference early after world leaders mocked him.

She argued that Democrats can't overlook that many Americans still support him and that it is her party's job to appeal to those people in a deeper way, invoking gut checks on decency, patriotism and values. "I don't agree with some of the candidates who think we should never talk about Donald Trump because I think we have to give people a reason and explain why we are better than him," she said.

Still, Klobuchar faces an uphill battle in coming weeks. While Buttigieg has been on the defense, fending off criticism of his corporate work and questions about his electability, he continues to soak up much of the oxygen in the race. Last weekend, he drew massive crowds across eastern Iowa, including 3,000 at a rally in Coralville, a Democratic stronghold.

Klobuchar faces other challenges too. Her moderate appeal means she'll struggle to draw the party's liberal voters. Her past as a prosecutor has made her candidacy a tough sell for nonwhite voters. And a January impeachment hearing will keep the senator in Washington a crucial moment.

And though voters at Klobuchar's campaign stops cheered, often wildly, as she made her case for how to take on Trump and why she believes she is the best candidate to do so, many weren't quite ready to back her campaign. Walking out of the events, several voters took commit-to-caucus cards but said they weren't ready to sign.

"I'm almost there," a woman told Klobuchar in Chariton last week. "I really like you."

Lisa Plein, a government worker from Dubuque, said she was leaning toward Buttigieg but also liked Klobuchar. But she worried about her electability. She recalled a recent conversation she'd had with her father, who railed against the idea of a female president. "I was like, 'Dad, you're saying this to your daughter?' " Plein said. "But I also realized there's a huge group of people who think like that . . . and how do you overcome that? . . . Defeating Trump is so important."

Klobuchar regularly nods to concerns about gender. In her stump speech, she argues a woman can beat Trump. "Nancy Pelosi does it every day," she said during the November Democratic debate.

But her more immediate dilemma isn't how she deals with the general election, but how she makes it out of the primary. Across the state, Iowans regularly speak of how much they like Klobuchar. "The ultimate compliment," she often jokingly says, comes from Iowans who say they like her so much that she's still in their top three.

Last week, Klobuchar, who is known for a dry, self-deprecating humor on the trail, sounded a little more anxious in her efforts to be more than just someone Iowans really like. "We're down to less than 60 days, so don't say, 'You're in my top three,' " she told the group in Chariton. With a smile and a voice dripping with mock exasperation, she pleaded, "Just make a decision!"