Asked by reporters about the plan, Mr. Trump made clear he was ready to do it, especially in California.
“They want more people in their sanctuary cities - well, we'll give them more people,” Mr. Trump said. “We can give them an unlimited supply.”
Democrats said the idea smelled of political retribution by a President who is frustrated that he cannot unilaterally impose his will on immigration policy, without first getting approval in Congress.
"Trump’s plan to release migrants into “enemy” cities as if they are some kind of contagion is reprehensible," said Sen. Ed Markey (D-MA).
"It seems there is no limit to how far Trump will go to degrade the office he holds," said Rep. Barbara Lee (D-CA), who noted in a tweet, 'here in California, we're proud' of sanctuary cities.
"It demonstrates an unimpeded desire to divide Americans against one another and again conveys once more his utter lack of fitness to serve as the leader of our nation," said Rep. Sheila Jackson Lee (D-TX).
Republicans have long chafed at 'sanctuary cities,' jurisdictions which refuse to cooperate with federal immigration authorities.