Democratic governors are urging President Donald Trump to back off his threats to deploy National Guard troops in cities led by his political opponents across the country.

A letter signed by most of the nation’s Democratic governors argues that Trump’s deployment of soldiers ostensibly to aid in civilian law enforcement is unnecessary and illegal.

“Whether it’s Illinois, Maryland and New York or another state tomorrow, the President’s threats and efforts to deploy a state’s National Guard without the request and consent of that state’s governor is an alarming abuse of power, ineffective, and undermines the mission of our service members,” they said in the letter, organized by the Democratic Governors Association.

Trump has deployed troops to Washington and Los Angeles and threatened to send them to Chicago and other cities led by Democrats in what he has portrayed as an effort to address violent crime, though the soldiers have done little in the way of law enforcement and overall criminality has declined in the U.S.

Trump made Washington the face of his crime crackdown in mid-August, taking control of the district’s police force and sending in the National Guard. The president has also floated plans to send the National Guard to Chicago, telling reporters at the Oval Office on Monday that it is “a killing field” and “disaster.”

California Gov. Gavin Newsom on Thursday announced a contrasting plan to send additional California Highway Patrol officers to several cities in the state to assist local law enforcement in addressing auto theft and drug crimes. Trump sent troops to Los Angeles in response to protests over the administration’s deportation agenda in June.

Chicago officials are preparing for the possible arrival of federal troops by dusting off plans they used for last year’s Democratic National Convention.

Four governors — Josh Green of Hawaii, Ned Lamont of Connecticut, Katie Hobbs of Arizona and Tim Walz of Minnesota — did not sign the letter.

“Every American deserves to feel safe in their neighborhood and community,” the governors wrote. “But instead of actually addressing crime, President Trump cut federal funding for law enforcement that states rely on and continues to politicize our military by trying to undermine the executive authority of Governors as Commanders in Chief of their state’s National Guard.”

White House spokesperson Abigail Jackson in a statement accused the Democrats of “doing publicity stunts,” and said their communities would be safer if they focused on combating crime instead of attacking the president.

“They should listen to fellow Democrat Mayor Muriel Bowser who recently celebrated the Trump Administration’s success in driving down violent crime in Washington DC,” she said.