FILE PHOTO: U.S. President Donald Trump speaks during a press conference in the Oval Office at the White House in Washington, D.C., U.S., October 15, 2025. REUTERS/Jonathan Ernst/File Photo

By Daniel Wiessner

(Reuters) -A federal judge on Tuesday extended a block that prevents President Donald Trump's administration from laying off thousands of federal employees amid a nearly month-long partial government shutdown.

During a hearing in San Francisco, U.S. District Judge Susan Illston barred nearly 40 federal agencies from implementing layoffs, pending the outcome of a legal challenge by unions representing federal workers. The decision extends an earlier temporary ruling.

The American Federation of Government Employees, which represents 800,000 federal workers and is a plaintiff in the case, this week called on Republicans and Democrats to put aside their differences and pass a spending bill so that government employees can return to work.

About 4,100 employees at eight agencies had been notified that they were being laid off before Illston's October 16 ruling, the Trump administration said in court filings. White House Budget Director Russell Vought has said that more than 10,000 federal workers could lose their jobs because of the shutdown.

Illston's decision will likely be immediately appealed, and could be paused by a San Francisco-based appeals court or the U.S. Supreme Court pending further litigation.

The shutdown, which entered its 28th day on Tuesday, is the second longest in U.S. history after a partial lapse in funding that lasted 35 days beginning in late 2018, during Trump's first term.

Trump has blamed Democrats for the shutdown and the planned layoffs, though no other administration has carried out mass layoffs during lapses in funding.

Trump's Republicans hold majorities in both chambers of Congress but need at least seven Democratic votes to pass a funding bill in the Senate, where Democrats are holding out for an extension of health insurance subsidies. Democrats have said they will not cave to Trump's pressure tactics.

The unions that filed the suit said implementing layoffs is not an essential service that can be performed during a shutdown, and that the current funding lapse does not justify mass job cuts because many federal workers have been furloughed without pay.

During Tuesday's hearing, U.S. Department of Justice lawyer Michael Velchik argued that federal agencies have broad powers to implement layoffs when they run out of funding to pay employees, and that Trump was following through on a campaign promise to reduce the size of the federal bureaucracy.

Danielle Leonard, a lawyer for the unions, countered that a funding lapse does not relieve federal agencies of their legal obligations under federal law or allow them to fire the workers who fulfill them. If it did, Trump could "fire the entire federal government" during a shutdown if he chose, she said.

Illston made clear throughout the hearing that she agreed with the unions.

"I believe I will find (the layoffs) are arbitrary and capricious, as shown by the haphazard way in which they were rolled out, and intended for the purpose of political retribution as Budget Director (Russell) Vought and the president himself have publicly announced," said Illston, an appointee of Democratic former President Bill Clinton.

Trump has, for example, said that job cuts would target "Democrat agencies."

Skye Perryman, president and CEO of Democracy Forward, a left-leaning legal group that represents the unions, said in a statement that the judge's ruling was a major blow to what it referred to as efforts by Trump to decimate the federal workforce.

(Reporting by Daniel Wiessner in Albany, New York; Editing by Edmund Klamann and Alexia Garamfalvi)