By John Fritze and Tami Luhby, CNN

(CNN) — The Trump administration asked the Supreme Court on Friday to reverse a lower court order that has blocked mass firings and major reorganizations at federal agencies, a case that could have enormous consequences on President Donald Trump’s ability to reshape the federal government.

The emergency appeal follows a decision from a federal court in California that temporary blocked the administration from conducting those layoffs and shrinking or eliminating entire components of agencies.

The lawsuit was filed by more than a dozen unions, non-profits and local governments, who are billing it as the largest legal challenge to the Trump administration’s effort to downsize the federal workforce. A senior administration official told CNN that it is watching the case closely because of its significance for allowing Trump to reduce the size and restructure the federal government.

The case stems from an executive order, which Trump signed in mid-February, kicking off the process of the federal employees’ mass culling. Agencies, which are working with Elon Musk’s Department of Government Efficiency to carry out the mandate, were required to file reorganization plans with the administration over the past two months. But the unions have complained that the details of those plans have not been shared.

Already, at least 121,000 federal workers have been laid off or targeted for layoffs since Trump took office, according to a CNN analysis. The figure doesn’t include those placed on administrative leave or those who took voluntary buyouts.

US District Judge Susan Illston’s temporary order on May 9 was among the most sweeping legal setbacks Trump and DOGE have faced in their efforts to drastically winnow down the federal bureaucracy.

The order covers major reductions at more than a dozen agencies, including the departments of Agriculture, Commerce, Energy, Labor, Treasury, State, Health and Human Services, Veterans Affairs and the Environmental Protection Agency.

“That far-reaching order bars almost the entire executive branch from formulating and implementing plans to reduce the size of the federal workforce,” US Solicitor General John Sauer told the Supreme Court in its appeal.

Illston held that Trump has the authority to seek changes to agencies but that he “must do so in lawful ways,” including consulting with Congress when large-scale reorganizations of federal agencies are involved.

“Many presidents have sought this cooperation before; many iterations of Congress have provided it,” she wrote. “Nothing prevents the president from requesting this cooperation – as he did in his prior term of office.”

The Trump administration sought emergency intervention from the 9th US Circuit Court of Appeals but, while that court set a scheduling for written arguments, it has not yet ruled on the request. Instead of waiting, the Justice Department went directly to the Supreme Court.

The administration argues Illston’s order is requiring it to maintain “a bloated and inefficient workforce while wasting countless taxpayer dollars.”

Illston, who President Bill Clinton named to the court, also ordered the administration to turn over records about its reduction plans. Trump attorneys told the Supreme Court that the requirement “threatens to reveal highly sensitive information that would undermine government operations.”

The Supreme Court is already considering nine other emergency cases dealing with Trump’s second term. The justices heard oral arguments in three of those on Thursday dealing with Trump’s efforts to end birthright citizenship and lower court orders that blocked him from enforcing that policy.

This story has been updated with additional information.

CNN’s Paula Reid and Tierney Sneed contributed to this report.

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