The Trump administration can move forward with plans to slash the federal work force and dismantle federal agencies, the Supreme Court announced on Tuesday. The decision could result in job losses for tens of thousands of employees at agencies including the Departments of Housing and Urban Development, State, Treasury and Veterans Affairs.

The order, which lifted a lower court’s ruling that had blocked mass layoffs, was unsigned and did not include a vote count, which is typical in such emergency applications. Justice Ketanji Brown Jackson wrote a public dissent.

The case represents a key test of the extent of President Trump’s power to reorganize the government without input from Congress. The justices’ order is technically only temporary, guiding how the administration can proceed while the challenge to Mr. Trump’s plans continues. But in practice, it means he is free to pursue his restructuring plans, even if judges later determine that they exceed presidential power.

It was the latest in a series of recent victories for the Trump administration before the Supreme Court on emergency requests related to the president’s efforts to rapidly reshape government.

The decision followed a major ruling on June 27, when the Supreme Court limited the ability of judges to block President Trump’s policies nationwide.

In recent weeks, the justices have issued other emergency decisions allowing members of the Department of Government Efficiency to gain access to sensitive records of millions of Americans held by the Social Security Administration; ending a humanitarian program intended to give temporary residency to more than 500,000 immigrants from countries facing war and political turmoil; and granting, for now, Mr. Trump’s request to remove the leaders of two independent agencies.