(Reuters) -A coalition of more than two dozen labor unions, cities and nonprofits sued President Donald Trump's administration, claiming that its broad federal workforce cuts were an illegal power grab.

The complaint filed on Monday in San Francisco federal court said the "large-scale reductions in force" that Trump ordered federal agency chiefs to implement on February 11 lacked Congressional approval, and violated the U.S. Constitution's separation of powers.

"When the President takes for himself the legislative power of Congress to recreate federal agencies in the manner he sees fit," the complaint said, "he threatens the very constitutional foundation of this nation."

Trump has said the cuts coordinated by the Department of Government Efficiency, which is overseen by billionaire Elon Musk, would transform the federal bureaucracy by eliminating "waste, bloat, and insularity."

The U.S. Department of Justice, which is among the defendants, did not immediately respond on Tuesday to a request for comment.

Plaintiffs in the case include the American Federation of Government Employees, the largest federal workers union with about 800,000 members, and the American Federation of State, County and Municipal Employees, with about 1.4 million members.

Local government plaintiffs include Baltimore, Chicago, San Francisco, and counties that include Houston and Seattle. Nonprofits that sued include the Alliance for Retired Americans, with 4.4 million members, and the Center for Taxpayer Rights.

The plaintiffs called their lawsuit the largest effort to stop Trump's job cuts. They said federal agencies had been required to submit job cutting plans on April 14.

In a statement, AFGE President Everett Kelley said Trump's cuts threatened "vital services Americans depend on every day--from caring for veterans and safeguarding public health, to protecting our environment and maintaining national security."

Baltimore Mayor Brandon Scott added in a separate statement: "Let's be very clear. The American people did not vote for this."

Since Trump took office on January 20, tens of thousands of federal workers have been fired, put on leave or quit.

Musk has tempered his original goal for DOGE to slash $1 trillion from government spending, saying this month it was on track to cut $150 billion this year.

The Trump administration has faced more than 200 lawsuits challenging its policies, with a significant number calling the president's directives unconstitutional.

The case is American Federation of Government Employees, AFL-CIO et al v Trump et al, U.S. District Court, Northern District of California, No. 25-03698.