By Maeve Reston, CNN

(CNN) -- As Kamala Harris introduced herself as a 2020 presidential candidate to Iowa caucus-goers and the nation on Monday night, she showed exactly why she is viewed as such a formidable contender.

During a CNN town hall at Drake University in Des Moines, she demonstrated an easy command of the policies that are most important to Democratic progressives in early states like Iowa. She was warm, witty and quick to laugh at the jokes audience members made at President Donald Trump's expense. She locked eyes with her questioners, responding to them by name and walking toward them as she answered, while displaying empathy for their struggles.

Perhaps most important, as Democrats weigh their options in the 2020 field, she made a succinct case for why she believes she would be the strongest candidate to take on Trump and not get "caught up in his crazy," as one questioner put it.

"It's very important that anyone who presents themselves as a leader, and wants to be a leader, will speak like a leader, and that means speaking with integrity — speaking the truth," Harris said. "And speaking in a way that expresses and indicates some level of interest and concern in people other than one's self."

"Right there we will see a great contrast," she said to laughter. She added the country deserves a leader who doesn't speak to "the lowest common denominators and base instincts and speak in a way that is about inciting fear as a distraction from the fact that you're getting nothing done, helping the richest people and the biggest corporations."

Her appearance at CNN's first town hall of the 2020 political season capped several weeks of events in which she has introduced herself and her biography to Americans. She officially announced her presidential bid on Sunday in her birthplace of Oakland, California, where thousands showed up hoping to catch a glimpse of her in the surrounding streets.

During the hour-long town hall, Harris staked out a set of progressive policy positions, including backing "Medicare for all" and doing away with private health insurance as well expressing support for a "Green New Deal" to address climate change. She also touted her plan to cut taxes for the middle class, saying it would be the first thing she would do if she were elected president.

She was passionate and definitive when she answered a question from a recipient of the Deferred Action for Childhood Arrivals program, commonly called "Dreamers," who told Harris that she didn't want to be used as a bargaining chip in the negotiations over a border wall. (Harris was the only potential 2020 presidential candidate who voted against the deal in February 2018 that would have created protections for Dreamers in exchange for wall funding).

"I will say to you, I stand with you," Harris said. "We should not be trading on your life."

The former California attorney general, who also served as district attorney of San Francisco earlier in her career, was also critical of her congressional colleagues who have failed to support gun control measures like the assault weapons ban after mass tragedies like the Parkland, Florida shooting and the massacre in Newtown, Connecticut.

She argued that her colleagues in Congress should have been forced to look at the autopsy photos of the "babies" who were killed in Newtown and then be asked to vote their conscience.

Listing the various proposals that have been introduced, she argued that legislators have no shortage of good ideas: "What's missing is for people in the United States Congress to act the right way."

Often on the campaign trail, Harris is quick to dismiss questions about what the historical significance would be if she were the first black woman elected president. She often deflects the question by quoting her mother, who told her, "You may be the first to do many things, but make sure you're not the last."

"That's how I think about those kinds of things," she said. But she went on to add that it would also be about "breaking barriers, it is something that is very important."

She added that she has had similar conversations with fathers and sons.

"I will also say to you that I have seen fathers bring their sons up to me and say, 'she is the first,' in a way that is to also speak to those sons about the fact they should not ever be burdened by what has been and they should see what can be," Harris said. "I think that's really the most important takeaway, which is that with each barrier we break, it is saying to all of us, don't be burdened by what has been. See what can be and strive for that."