Senator Cory Booker, tieless and in a blazer on the southwestern border in early July, approached a Customs and Border Protection officer, blue passport in hand. They greeted each other and the officer asked: “Is there somebody with you?” Yes, Mr. Booker said, he had a group with him.
Specifically, Mr. Booker said, he was traveling with a group that included five women, all survivors of domestic violence in their home countries, Cuba and Honduras, who were seeking asylum in the United States. They had been sent back to wait in Mexico once before.
But now they had a high-profile senator and 2020 presidential candidate with them, and he had a slew of cameras and reporters waiting across the border for him.
Those cameras were on hand to capture the women walking across the bridge from Mexico, and were around later to hear the senator announce that the women were allowed to continue into El Paso and take refuge in a shelter while their applications would be processed. He stayed on a street corner to answer questions from reporters for about 10 minutes.
Throughout his political career, which began on the Newark City Council in 1998, Mr. Booker has expressed clear political principles — a desire to fight for equality and fairness — and he has made those principles clear in the usual ways politicians do: speeches, slogans and policy proposals.
He has also moved into a decrepit housing complex, staged a 10-day fast and slept in a tent near a popular spot for drug dealers, a tactic of physical advocacy that emphasizes showing up and being present for the issues he’s fighting for.
This style has led to change, from improvements to public housing in Newark to migrant women being granted the opportunity to remain in the United States while pursuing asylum claims.
The Booker-accelerated change, of course, often starts with the media coverage he commands. As he becomes a part of the story, he elevates both the issue and his own visibility.
Mr. Booker brought that style to the southwestern border Wednesday — at a moment when he is in seventh place in most national polls — and physically inserted himself into a major issue for Democrats in the primary campaign in an unusual fashion.
While many of the presidential candidates, including Mr. Booker, have visited immigrant detention centers along the border before, none had taken the step of physically observing the entire asylum process. Mr. Booker used his role as a senator to assist the people seeking asylum and to experience the uncertainty and logistical challenges of the Trump administration’s tamping down on asylum claims.
“This was a heartbreaking day to hear firsthand from the people who are escaping individual terror,” Mr. Booker told reporters on a street corner in El Paso minutes after crossing back into the United States. He described his view of the asylum process, and how it was compounding trauma. “The system that this president has created is unacceptable,” he said.
In the summer of 1999, Mr. Booker, then a City Council member, and his supporters staged a 10-day vigil outside of housing projects in Newark’s Central Ward to draw attention to a booming open-air drug trade that residents said was threatening their safety. Over the course of the 10 days, local media outlets began to show up, and the vigil itself became a story. Eventually, Mayor Sharpe James put in place a 24-hour police van and a new security fence, and he later promised a new park for the project.
The following year, Mr. Booker took his crusade to Newark’s other wards, spending five months in a motor home, going from neighborhood to neighborhood, to highlight the plague of drugs and guns in the city’s poorest areas. Suddenly, a city councilman from Newark was getting interviewed on C-Span and CNN.
Shortly after becoming a councilman, Mr. Booker moved into Brick Towers, a 20-story housing complex in the Central Ward. The building, once a safe and desirable place to live, had become a hub of drug activity and other crime.
For Mr. Booker, it was an opportunity to experience firsthand the struggles he had never had to overcome growing up in the wealthier New Jersey suburbs. But it also brought attention to a housing complex that had long been forgotten.
“There was a time when drug dealers had lines out of the building, but it just ended as soon as he moved in,” Jimmy Wright, a former Newark police officer and Booker supporter who lived in Brick Towers, said in an interview.
He remembered that just having a city councilman in the building brought new security, functional elevators and maintenance crews to the towers. “You didn’t smell urine, you smelled pine again,” Mr. Wright said.
When Mr. Booker decided to run for mayor of Newark in 2002, he brought along a documentary crew to film his upstart challenge to Mr. James, showing a national audience the squalor of the housing complex he called home and the corrupt machine that dominated city politics. The film, “Street Fight,” would eventually be nominated for an Academy Award.
“That mixture of policy wonk and street-level activist were what interested me in him in the first place,” said Marshall Curry, the director of the documentary.
Mr. Curry recalled talking to Mr. Booker recently about the lessons he learned from the documentary process. “He felt like he learned that there was value in opening up to the media and letting people see him as he really was, struggle and all, warts and all,” Mr. Curry said.
Soon enough, Mr. Booker’s penchant for camera-friendly interactions garnered broader national attention and became a bit of a pop-culture phenomenon. Shortly after becoming mayor, he chased down a bank robber in broad daylight, earning national headlines. He ran into a burning building to save a woman. He rescued a freezing dog left outside during a cold snap, responding to a tweet from a local reporter. He shoveled driveways and delivered diapers during snowstorms.
His daring antics earned him a spot on the couch of Ellen DeGeneres, who gave him a Superman cape.
At home, however, the showy displays began to irk residents, as some felt that they masked larger shortcomings.
“The only reason he brought me Pampers was that it had been three days and our street hadn’t been plowed,” Barbara Byers, a Newark resident, told Politico in 2016. She received a diaper delivery from Mr. Booker after tweeting about being homebound in a snowstorm.
“I have five kids and, trust me, I don’t just run out of Pampers,” she said. “All we wanted was for him to plow our streets. It’s about knowing how to manage a city.”
In the Senate, his action-oriented style drew some derision on cable news and social media when he released confidential documents (some of which were actually declassified) during the confirmation hearing for Justice Brett M. Kavanaugh — and called it a “Spartacus” moment.
To Mr. Booker, however, all attention was for the greater good of bringing attention to Newark and other causes he wants to champion.
In what has become a regular part of his presidential stump speech, Mr. Booker recalls a spat he had with Conan O’Brien over a joke: The late night host said that a new health care plan introduced by Mr. Booker “would consist of a bus ticket out of Newark.”
In his telling, Mr. Booker saw the dig as an opportunity.
“Before I know it, I’m getting earned media like I never got before,” Mr. Booker said on a campaign stop in Bedford, N.H., in April. “I bragged about my city with more American eyes watching than ever before.”