This post has been updated.
Twenty-three mayors, including New York's Bill de Blasio, Los Angeles's Eric Garcetti, Houston's Annise Parker and the District's Vincent C. Gray have joined the group.
"The president's action on immigration will strengthen our cities. It will keep families together, grow our economies and foster additional community trust in law enforcement," the mayors said in a statement. "We are ready -- and together we're rolling up our sleeves to turn this policy into a better reality for millions of hardworking people in the communities we serve."
One of the goals of the group is to send a message that immigrants are welcome in, and a crucial part of, the cities represented and the nation as a whole. They also are trying to delineate between the roles of federal immigration enforcement and local law enforcement.
The mayors will meet in New York on Dec. 8.
"This summit will offer a unique opportunity for mayors of many of our nation’s progressive cities to restate our leadership and responsibility on this decisive issue," de Blasio said in a statement released after Obama's announcement. The group will sketch out a plan "that truly prepares our localities for swift implementation of changes and also advocates for further reforms from the municipal level all the way up to Washington.”
Pittsburgh Mayor Bill Peduto said he is a "firm believer in the power of cities taking control of their future," and that mayors who work together strengthen their cities.
"Immigrants in Pittsburgh today mirror the same drive that was true generations ago with the arrival of Irish, Italian, Polish, German, and many others who helped to build our city, and our country," Peduto said in a statement. "Our city's resiliency and can-do work ethic carries on in new immigrants who are opening small businesses such as grocery stores and retail shops, launching careers in our budding tech start-up industry, and setting roots across our city."