DES MOINES, Iowa — Cory Booker's voice is shot. Standing on stage before hundreds of potential voters in the state that boasts the pivotal first-in-the-nation caucus, Booker, in a raspy voice that normally booms, is adamant his message of love, hope and unity can win him the Democratic nomination and, ultimately, the presidency.

"They're going to say, 'Oh my gosh, more candidates talking about love and hope; oh my God, how are you going to beat Donald Trump with that?'” the New Jersey senator, 49, told the packed venue at his last event in the state following a two-day blitz through five other cities in below-freezing temperatures.

“I want to see that man out of the White House, but I was called to dream bigger than that. ... This is a test to see how much we can unite America,” he said.

Sen. Cory Booker, D-NJ, speaks at a campaign stop at the Des Moines Social Club in Iowa on Feb. 9, 2019. Scott Olson / Getty Images

It could be a risky message given that a recent Monmouth University poll found Democratic voters prioritizing "electability" over values in 2020. But dozens of potential voters and community leaders who spoke to NBC News as Booker zipped through Mason City, Waterloo, Cedar Rapids, Iowa City, Marshalltown and Des Moines said they were compelled by his story of turning around a beleaguered urban city as mayor of Newark, his work as a senator and his message of bringing the country together.

Rita Robinson, 63, a member of the Cedar Rapids chapter of the National Association for the Advancement of Colored People, saw Booker speak for the first time at his stop at the city’s African American museum and made up her mind.

“He is my candidate. He talked to all of us in the room,” she said, noting the crowd was largely white with a few black residents in attendance. “I think they look at Cory and remember when Obama was president — they backed him because they believed in the message.”

Robinson added, “He’s got the vocabulary, the know-how and knows how to throw in a little bit of the hood. … He’s like, ‘I’m different, but I’m not different from you, and I know how to get things done.’”

'I had to run something'

A question that dogged Booker in his pitch to voters in Iowa is what makes him different from the other Democratic candidates. Sens. Elizabeth Warren of Massachusetts, Kirsten Gillibrand of New York and Kamala Harris of California have already visited the state, and so far there is not much the contenders disagree on when it comes to hot-button issues like health care, education and climate change.

But at a campaign event in Mason City, Iowa, Booker pushed back on Harris' idea of doing away with private health insurance to achieve single-payer health care, or Medicare-for-all. He also frequently touted his role in shepherding Trump's criminal justice reform bill through the Senate last year, even noting how he won over the support of Iowa's Republican Sen. Chuck Grassley.

Former mayors are rarely candidates for the White House, according to a 2018 study in the journal American Politics Research. But Booker plugged his work in Newark as a microcosm of what he can do at the national level. He claimed to have turned around its schools and improved its local economy.

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"I’m friends with these folks," he said of his Democratic rivals in remarks at a packed brewery in Marshalltown. "I’ve written legislation with these folks. But I want to tell you some things unique about me so you just know: I had to run something. And it wasn’t just something — it was a very challenged city. I had to manage it through the worst economic crisis of our lifetime. I had to stand in the saddle and make difficult, difficult decisions."

Sen. Cory Booker, D-NJ, speaks to guests at a campaign event at the First Congressional United Church of Christ in Mason City, Iowa, on Feb. 8, 2019. Scott Olson / Getty Images

Booker, who is vying to be the nation’s second black president, also made overt references to race in his first visit here as a 2020 candidate. African Americans make up a crucial voting bloc of the Democratic party and represent 3.8 percent of Iowa's total population. Booker’s message of unity was often centered on improving race relations in the country, focusing on issues such as income inequality, voter suppression and racial disparities in the criminal justice system.

He also discussed at length his family’s struggle to integrate a white New Jersey suburb in the 1960s, saying real estate agents would not sell them homes until white volunteer lawyers worked together with black housing activists to confront the issue.

“We have to be able to talk about race in America,” Booker told a largely white crowd at the brewery in Marshalltown. “You can’t have reconciliation without truth-telling.”

He added, "Right here in Iowa, people meeting in barns, white folk and black folk, built the greatest infrastructure project this country has ever seen: The Underground Railroad," referring to the network of white and black Americans who aided slaves through a network of safe houses to free states.

“I think he’s got it, he’s like magic,” said 72-year-old Ruth Cody Brewer, who lives in Forest City and works on the Wing Ding committee, a grassroots fundraising effort for the state Democratic Party, after a campaign event in Mason City. “He energized me today.”

Other voters, however, were not completely sold but noted that Booker stood out among the declared candidates.

“I think it’s time for a reformation. Is he a great reformer like the Kennedys or the Roosevelts? I don’t know,” said Mark Suby, a Mason City resident and retired city parks superintendent. “But he’s certainly on my list.”

'I’m confident in my toughness'

For Booker, another important issue is trying to win over Trump voters, saying "they feel lost, they feel forgotten, they feel even attacked."

"I believe strongly they voted wrong, but if we don’t speak to their pain, if we don’t talk with our ideas and our heart and our empathy and our policies that will deal with these issues, we’ll never get those voters back," he said.

He also spoke at events about his friendships with Republican lawmakers, such as former Sens. John McCain and Jeff Flake, both of Arizona, and reaching across the aisle in the Senate to get legislation passed.

“I’m running not just to beat Republicans, I’m running to unite Americans,” Booker said at an event in Mason City.

He added, “At this time in our country, we don’t need to fight fire with fire.”

Chris Peterson, a 64-year-old farmer who was an Iowa delegate for Vermont independent Sen. Bernie Sanders at the 2016 Democratic National Convention, said Booker is going to “take the torch and have courage,” but “unity is only going to go so far.”

“Don’t compromise the issues away to get Republican support,” he said. “Democrats have caved over the years.”

But Booker, a former college football player, told voters he can take whatever is thrown at him, especially if he’s up against Trump, a self-professed counterpuncher.

"There is nobody in this race tougher than me ... " Booker said. "But we have got to stop in this country thinking that to be tough you have to be mean, to be strong you have to be cruel. That is a lie. The most powerful force in this universe is defiant love. And I will stick by that."

“If we try to fight Donald Trump on his turf, not only will both of us get muddied, but the country suffers as a result. And so I’m confident in my strength. I’m confident in my toughness."