DENVER – On Friday, the Department of Justice took legal action against Colorado and Denver, accusing them of obstructing federal initiatives to enforce immigration laws. This is part of the Trump administration’s broader effort to curb what are referred to as sanctuary cities and policies.

The lawsuit asserts that both the state and its capital, Denver, have enacted “sanctuary laws” that are in contravention of the Supremacy Clause of the U.S. Constitution.

“The United States has well-established, preeminent, and preemptive authority to regulate immigration matters,” states the lawsuit, which was lodged in the federal court in Denver.

There is no strict definition for sanctuary policies or sanctuary cities, but the terms generally describe limited local cooperation with Immigration and Customs Enforcement. ICE enforces U.S. immigration laws nationwide but seeks state and local help, particularly for large-scale deportations, and requests that police and sheriffs alert ICE to people it wants to deport and hold them until federal officers take custody.

The Department of Justice has filed similar lawsuits against Chicago and Rochester, New York.

Justice Department attorneys argue Colorado’s “sanctuary policies” allowed the Venezuelan gang Tren de Aragua to seize control of an apartment complex in the Denver suburb of Aurora.

Local officials have called Trump’s claims that the gang had taken over large swaths of the city exaggerated, but acknowledged the apartment complex was terrorized, including by people linked to Tren de Aragua.

Friday’s lawsuit lists as defendants Democratic Gov. Jared Polis, the state Legislature, Denver Mayor Mike Johnston and Colorado Attorney General Phil Weiser.

Polis spokesperson Conor Cahill said in an email that Colorado is not a sanctuary state and regularly works with local, state and federal law enforcement agencies.

“If the courts say that any Colorado law is not valid then we will follow the ruling,” he said. “We are not going to comment on the merits of the lawsuit.”

Republicans in Congress have pressured officials in Democratic-led cities to cooperate with the Trump administration’s immigration agenda. Lawmakers summoned the mayors of Denver, Boston, New York and Chicago to testify last month before the House Committee on Oversight and Government Reform.

The mayors pushed back, defending their communities as welcoming places, not lawless danger zones, and called on Congress to pass immigration reform.