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."