The loudspeaker on a quiet Staten Island street blasted demands at 117 decibels, louder than a dog barking in your ear. Pointed at a school that is sheltering some of the 110,000 migrants who have arrived in New York City over the last year and a half, the message could not have been more unwelcoming: “Immigrants are not safe here.”

The influx of migrants from the southern border has strained city resources, put pressure on local leaders, and scrambled the political playing field. Now, angry protests over the crisis and the city’s response to it appear to be reaching a fever pitch.

The demonstrations have increased in vitriol as Mayor Eric Adams has sharpened his own rhetoric. “This issue will destroy New York City,” he told New Yorkers last week, and a variation on those words has shown up on at least one demonstrator’s sign.

The front line of the fight is in Staten Island, the city’s most conservative borough, where roughly 2 percent of the 59,000 migrants living in homeless shelters are housed at a former school, St. John Villa Academy. At an anti-migrant rally on Staten Island Thursday night signs reading “Protect our Children” were nailed to utility poles. Protesters wore shirts emblazoned with American flags and images of former President Donald J. Trump’s face.

John Tabacco, a Newsmax host, rallied the crowd from a black pickup truck.

“This is the first place where they’re trying really infringe on our liberties and our freedoms,” Mr. Tabacco told the protesters. “This is the hill I want to die on. Because if we break here, we break everywhere.”

At a rally at Floyd Bennett Field in Brooklyn Thursday evening, Curtis Sliwa, founder of the Guardian Angels, told the enthusiastic crowd: “This is our battle for our neighborhoods, for our children, for our grandparents. For your equity.”

Mr. Sliwa, who ran against Mayor Eric Adams in 2021, added: “This is a battle for our city.” The World War II naval air base in Brooklyn is slated to house 2,500 male asylum seekers.

The former Staten Island school’s location in a residential neighborhood a few blocks from the Verrazano Bridge, as well as its proximity to other, active schools, has made it a lightning rod for anti-migrant protests. At a house on a nearby street, homeowner Scott Herkert planted a profanely worded sign, made from a blue tarp and two wooden posts, with the message: “No Way,” with the profanity obscured.

Mr. Herkert said his protest was prompted by the temporary showers and bathrooms that have been installed close to his backyard, which overlooks the school grounds.

“This is not the right place for this,” Mr. Herkert said. “This is a sleepy neighborhood, very quiet, you have residents all around.”

Mike Holder, 46, a lifelong Staten Island resident, said his sister’s daughter attends the school across the street from the shelter.

“She’s worried,” Holder said of his sister. “I think people should stand up, get in the streets. I don’t think there’s enough people here. Maybe it’s got to get worse. Maybe it’s got to get worse before it gets better.”

In August, after weeks of protests over the school being used as a shelter, Staten Island officials went to court to block the city’s plans, and secured a brief victory when a judge issued a temporary restraining order that prevented city officials from placing migrants at the St. John Villa Academy shelter, as reported by the Staten Island Advance.

But the city won its emergency appeal and the judge’s ruling was overturned. So residents turned to other measures — heckling migrants who came looking for shelter and protesting loudly.

Then the speaker appeared.

Blasting a rotation of messages in five different languages, according to reporting by the New York Post earlier this week, the speaker was only a little quieter than a siren. It was on Mr. Herkert’s street, but he and others residents would not confirm whether they owned it. The speaker is not currently broadcasting.

Gisela Rivadeneira, 24, and her father, Roberto Rivadeneira, 52, both originally from Ecuador, have been staying at the shelter since they arrived there 12 days ago. There are just a few more weeks before a 60-day deadline to move out, which the Adams administration recently imposed on migrants.

The messages from the speaker over the weekend underlined the feeling that they are not welcome.

“We are not afraid of the neighbors, because we are not doing anything wrong,” Mr. Rivadeneira said, adding, “We did not cross into the country illegally.” He added that they were paroled into the U.S. at the border and have an immigration court date in the future.

Ms. Rivadeneira also argued that they had come the right way.

“They think we come to do bad things, but in reality the United States is built on the backs of Latinos. We come to work. We don’t bother anyone,” she said.

The two had spent the day in Queens — a three-hour round trip — canvassing every Spanish-speaking restaurant and store for open positions. But no one was hiring. Their plan was to wake up early tomorrow to try again.

The migrants in the New York City shelter system are spread out across the city and have come from across the globe — from Venezuela, Colombia, Senegal, Mauritania, even Madagascar. They survived dangerous journeys to the United States’ southern border, hoping to be rewarded with safety and opportunity. New York has struggled to provide both, and the city’s tradition of welcoming immigrants is increasingly frayed.

While New York is overwhelmingly Democratic, the protests in right-leaning areas like Staten Island and Southern Queens are a reminder of its political divisions. But they have also cropped up in unexpected places, like Sunset Park, a neighborhood heavily populated by immigrants.

“Immigrants that have come here illegally, they’re taking the easy path,” said Shirley Marquez, 66, who lives in Queens and attended a protest at a temporary shelter there last month. “They’re not being vetted.”

Whether migrants have been “vetted” has become a common concern voiced by conservative leaders and protesters.

“Does the N.Y.P.D. vet those individuals?” Representative Nicole Malliotakis, whose district includes Staten Island, asked during a House Subcommittee on Emergency Management and Technology hearing Tuesday.

Like the Rivadeneiras, many migrants in New York City have first checked in with the Border Patrol before being released into the country and traveling to New York.

“Nearly every single one has come through a port of entry, has been vetted and has gone through that process,” said Representative Dan Goldman, D-N.Y., at the same hearing.

Sandra Ramírez, 24, a lifelong resident of Staten Island and daughter of immigrants from Puebla, Mexico, has been going around the neighborhood taking down anti-immigrant signs every time she sees one.

“I do it because this affects us all. I think about my parents and how they must feel,” she said, adding, “I do not agree with these types of signs because they only foment violence.”

Olivia Bensimon, Joshua Needelman and Holden Velasco contributed reporting.