Democratic opponents of the GOP governors who are flying and busing migrants to cities and towns in the northeast U.S. from border states are calling for legal action to halt the tactic and potential criminal prosecution of those responsible.

In a series of television appearances Sunday, New York City’s mayor, Eric Adams, said his administration is considering legal challenges to the Texas governor’s practice of chartering buses to ferry migrants to his city from cities along the U.S.-Mexico border.

“We believe there are some options we have, because when you involuntarily place someone on a bus, we believe that actually skates the law,” Mr. Adams said in an interview on the New York CBS affiliate. “We’re not leaving any stones unturned to make sure that New Yorkers are [not] being treated in an unfair way.”

Lawyers working with a group of migrants who were flown to Martha’s Vineyard last week by Governor DeSantis of Florida asked federal and state officials in Massachusetts to open a criminal investigation into the incident.

In letters to both the U.S. attorney in Boston, Rachael Rollins, and the attorney general of the state of Massachusetts, Maura Healey, a group that claims to be representing as many as 30 of the Venezuelan migrants who were dropped off on the island — Lawyers for Civil Rights — said its clients were unlawfully duped into boarding the planes and crossing state lines. The lawyers said they “strongly believe that criminal laws were broken by the perpetrators of this stunt.”

“Individuals, working in concert with the Florida Governor, made numerous false promises to our clients, including of work opportunities, schooling for their children, and immigration assistance, in order to induce them to travel,” the letter to the U.S. attorney states. “It was only when the flight was in mid-air that they were informed they would be flown to Martha’s Vineyard, rather than to Boston as many had been told.”

At a forum sponsored by the Boston Globe Friday, Ms. Rollins said she would be consulting with officials in other cities affected by the Republican governors’ tactics — including Chicago, Washington, D.C., and New York — to determine if any laws were broken.

“We are going to be looking long and hard, as the federal government in the commonwealth of Massachusetts, to see any and all legal action that we might be able to take,” Ms. Rollins said.

At a  news conference Friday, Mr. DeSantis defended his decision regarding the flights, stating that the passengers all signed release forms and were fully informed of their destination and given information packets about the island. Far from backing down on the tactic, he promised similar charter flights to “a whole bunch of other places” in the near future.

As Mr. Adams was making the rounds of television interviews on Sunday, another six buses full of migrants from the border showed up at the city’s Port Authority bus terminal. At least 2,500 of the migrants delivered so far have ended up in New York’s homeless shelters, pushing the system to what Mr. Adams called a “breaking point.”

Mr. Adams said the city, which has opened up 23 new shelters so far to cope with the influx and plans on opening 38 more, is contemplating bringing in a cruise ship to house the newcomers.

The Republican governors are sending the buses and planes to protest the Biden administration’s policy of allowing thousands of asylum-seeking migrants into the country every day. The migrants — who are processed by immigration officials and then released pending court hearings — are overwhelming both federal immigration facilities and social services such as shelters and food pantries in the small towns along the border, they say.

A Democratic congressman representing a district in South Texas on the border, Henry Cuellar, decried the “theater” of busing the migrants out of the border states, but said more resources are needed at the border to bring the situation under control. Existing immigration laws are not being enforced, he said, and the migrants as well as the smugglers who prey on them know that.

“If we don’t have repercussions at the border, we’re going to continue getting 8,000 people a day,” Mr. Cuellar said in an appearance on CBS’s “Face the Nation.” “They might get two buses a day in some of those cities. Just for my hometown in Laredo, we’re sending out 21 to 26 buses a day out of Laredo, just to give you an idea of what’s happening here.”