PORTSMOUTH, N.H. >> Nearing the end of a lively town hall with hundreds of voters packed into an art gallery, Cory Booker surveyed the crowd and reassured them that his sunny, unity-first presidential campaign is also tough.

“People who think my philosophy is weak, come on,” the New Jersey Democratic senator said, chiding those in his party who would try to simply “fight fire with fire.” He later described himself to reporters as “someone who’s strong, who’s tough, who will fight for a cause and fight for people but also finds common ground.”

Booker is trying to be the nation’s healer and warrior. After launching his campaign this month with a warm pitch to restore America’s “common purpose,” he’s talking more about confrontation. That approach during a recent three-day swing through the early-voting state of New Hampshire seemed to acknowledge that optimism will only carry him so far and that some Democratic voters outraged by President Donald Trump’s agenda want more.

“What I saw in the last election was that, Republicans and especially Trump, they’re not afraid to just lie right on the stage during a debate,” said Sebastian Young, of Dover, New Hampshire, who saw Booker at an event on Sunday. “So he has to be willing to call that out, and really, like, press it when Trump is saying something that’s not true, or that goes against what he believes.”

Many of Booker’s Democratic rivals have more openly channeled their base’s fury with Trump. Hours after Booker left New Hampshire, voters there cheered California Sen. Kamala Harris’ vows to take on the president. In California, Sen. Elizabeth Warren of Massachusetts urged Americans “to fight hard, and to win.” And in Iowa on Monday, New York Sen. Kirsten Gillibrand shared none of Booker’s reluctance to call Trump a racist.

“I think he’s racist when he says that Mexicans are rapists and criminals,” she told reporters.

Referring to Booker, one of two black Democratic presidential candidates, as a “really good friend of mine,” Gillibrand added that “each one of us will run on our vision and what our plans are.”

Democratic candidates are spending the early days of the campaign fleshing out their vision of how to best challenge Trump and whether to respond to his kitchen-sink fighting style with similar force.

“We have to figure out what we want. Is it the fighter from the outside, or the person who can work the room?” said Rebecca Katz, a New York-based progressive political strategist. “In some ways, to win any big change, you need both. And it’s unclear if you can be the fighter in the room and still go out there and motivate activists who make real change.”

For now, Booker is arguing that he can do both, vowing in New Hampshire that a fight waged with “love … can topple the strongest of leaders.”

The 49-year-old has demonstrated a willingness to enter nasty political frays. His self-proclaimed “‘I am Spartacus’ moment” last year came as he willfully flouted Senate rules against disclosing confidential documents during Brett Kavanaugh’s Supreme Court confirmation fight. He made history for testifying against a fellow sitting senator in 2017 when he publicly opposed Republican Jeff Sessions’ bid to become attorney general.

One of Booker’s closest friends on Capitol Hill, Hawaii Democratic Sen. Brian Schatz, said his colleague “is hard to put in a box.”

“There is literally no one like him,” Schatz said in an interview. “And he’s so pure of heart that people may mistake that for an unwillingness to engage in fights when necessary. That’s not the case when it comes to Cory.”

Sen. Richard Blumenthal, D-Conn., who serves with Booker on the Judiciary Committee, said the intense Kavanaugh hearings were “not even the best example” of his colleague’s presence as “a fierce and tenacious fighter.”

Still, positivity is central to Booker’s political brand. He splashed onto the national scene by shoveling snow as Newark mayor. In the Senate, he’s built alliances with Republicans on legislation protecting special counsel Robert Mueller and on passing a Trump-backed criminal justice deal.

New Hampshire will be a tough state for many Democrats, with big names from neighboring states — Warren and Vermont Sen. Bernie Sanders — in the race. But Booker’s dual message of coalition-building first and fighting when necessary played well with voters during his first official visit as a candidate.

Maggie O’Neill, a Newmarket resident, said she understood his interest in being “seen as an individual” rather than boxed into a stereotype.

“It’s hard when you’re running a campaign. You have to fit into a trope, right? Everybody wants to put you into a trope,” she said.

Booker, like other Democrats in the still-forming primary field, has only begun to build his case as the candidate who can both charge into battle and unify a party desperate to defeat Trump. So far, he’s making a big push for the film “Street Fight” to underscore his warrior instincts. Supporters who sign up for his campaign email list get an automatic reminder to watch the Oscar-nominated film that illustrates “how fearless he is in the face of a fight some think is impossible.”

The documentary about Booker’s 2002 mayoral run depicts him weathering repeated low blows from his then-opponent, Democrat Sharpe James, who ultimately defeated him but bowed out of a rematch in 2006. Booker cruised to victory that year on his way to winning a special election to the Senate in 2013, and he secured a full term in 2014.

Asked if he had played up his time in the pressure cooker of New Jersey politics to portray himself as a candidate who can go toe-to-toe with Trump, he demurred.

“I just talk about that because I’m a Jersey boy who’s had to fight a lot of tough elections,” he told reporters.