WASHINGTON — The Supreme Court on Tuesday refused to allow the Trump administration to deploy National Guard troops in the Chicago area to support its immigration crackdown, a significant defeat for the president’s efforts to send troops to U.S. cities.

The justices declined the Republican administration’s emergency request to overturn a ruling by U.S. District Judge April Perry that had blocked the deployment of troops. An appeals court also had refused to step in. The Supreme Court took more than two months to act.

Three justices — Samuel Alito, Clarence Thomas and Neil Gorsuch — publicly dissented.

The high court order is not a final ruling but it could affect other lawsuits challenging President Donald Trump’s attempts to deploy the military in other Democratic-led cities.

“At this preliminary stage, the Government has failed to identify a source of authority that would allow the military to execute the laws in Illinois,” the high court majority wrote.

Justice Brett Kavanaugh said he agreed with the decision to keep the Chicago deployment blocked, but would have left the president more latitude to deploy troops in possible future scenarios.

The outcome is a rare Supreme Court setback for Trump, who had won repeated victories in emergency appeals since he took office again in January. The conservative-dominated court has allowed Trump to ban transgender people from the military, claw back billions of dollars of congressionally approved federal spending, move aggressively against immigrants and fire the Senate-confirmed leaders of independent federal agencies.

Democratic Illinois Gov. JB Pritzker applauded Tuesday’s decision as a win for the state and country.

“American cities, suburbs, and communities should not have to face masked federal agents asking for their papers, judging them for how they look or sound, and living in fear that the President can deploy the military to their streets,” he said.

White House spokeswoman Abigail Jackson, on the other hand, said the president had activated the National Guard to protect federal personnel and property from “violent rioters.”

“Nothing in today’s ruling detracts from that core agenda. The Administration will continue working day in and day out to safeguard the American public,” she said.

Alito and Thomas said in their dissent that the court had no basis to reject Trump’s contention that the administration needed the troops to enforce immigration laws. Gorsuch said he would have narrowly sided with the government based on the declarations of federal law enforcement officials.