The dozen demonstrators - including children whose parents face deportation - squeezed into a narrow corridor at Philadelphia City Hall.
They came bearing posters urging Mayor Nutter to end the five-year-old agreement in which the city Police Department shares arrest data with the U.S. office of Immigration and Customs Enforcement (ICE).
Kneeling in his tan suit to meet the youngsters eye-to-eye, Sgt. Michael Walton, head of the mayor's plainclothes protection unit, was gentle.
"Step forward," he encouraged one girl. "Do you want to sign that poster? I will give it to the mayor. . . . What do you want him to know?"
A confident boy, about 9, said that the ICE-police collaboration was "tearing" immigrant families apart and that these kids, who represented the New Sanctuary Movement of Philadelphia, an immigrant support group, hoped the mayor would end it.
The agreement to share data from the police department's Preliminary Arraignment Reporting System, PARS, has been renewed annually since 2008.
It is due to expire Saturday but is likely to be renewed.
After City Hall, the demonstrators marched to the office of District Attorney Seth Williams, where a random encounter at the front door with the DA, who seemed dressed for a day off in cargo shorts and an Under Armour shirt, promised to read the material the children dropped off.
Williams, along with Municipal Court President Judge Marsha Neifeld and Police Commissioner Charles Ramsay, have input into the decision to renew or halt the license, which gives ICE real-time access to PARS in exchange for an annual fee of $5,565.
Newark, N.J., Princeton, and New Orleans are among cities that have opted out of such arrangements, saying they do more harm than good because undocumented immigrants won't report crimes if they fear that doing so will get them targeted by ICE.
In 2010, responding to those concerns, Nutter ordered all victim, witness and complainant information scrubbed from PARS before ICE gets to browse it.
Everett Gillison, deputy mayor for public safety, has said that step is sufficient to address critics' concerns.
Nonetheless, say some critics, the collaboration sends the wrong message about whether immigrants can feel comfortable approaching police.
Another sharing agreement, called "secure communities," notifies ICE when an individual in local police custody has his fingerprints checked against the FBI's fingerprint database. If the person's prints match those of someone whom ICE suspects of being here illegally, a detainer issues and the person is transferred to ICE custody and probable deportation proceedings.
PARS is the bigger threat to undocumented immigrants, critics contend, because it updates automatically and can be used more casually by ICE.
The result, they say, is that those stopped for minor traffic offenses could find themselves facing deportation, affecting whole families, including their U.S.-born children.
"Some cities are stepping up to end this collaboration," said New Sanctuary community organizer Blanca Pacheco.
"The city talks a lot about Philadelphia being a welcoming place," said Pacheco. "We want them to welcome everyone."