WASHINGTON — A US judge on Thursday temporarily blocked President Donald Trump's proposed buyout for federal workers until at least Monday, giving an initial win to labor unions that sued to stop it.

Even as the program was stayed, more than 60,000 federal employees had already accepted the buyout offer, a White House source told Reuters.

The ruling by US District Judge George O'Toole in Boston pushes back a midnight deadline set by the Trump administration, which is pressuring federal workers to leave their jobs in an unprecedented drive to overhaul the federal government.

O'Toole could opt to delay the buyout further or block it on a more permanent basis when he next considers the legal challenge by the unions at a hearing on Monday.

The buyout effort is part of a far-reaching plan by the Trump administration to both rein in and reduce the size of the federal bureaucracy, which Trump blames for stymieing his agenda during his first presidential term.

The proposal has upended Washington, sparking street protests and accusations from labor unions and opposition Democrats that the Republican president is violating multiple laws.

Federal employees were asked to indicate they wanted to take part by typing RESIGN into the subject line of an email from their government accounts.

The offer promises to pay employees' regular salaries and benefits until October without requiring them to work, but that may not be ironclad. Current spending laws expire on March 14, and there is no guarantee that salaries will be funded beyond that point.

The Education Department told staffers that those who accepted the buyout could see their paychecks stop at any time, media outlets reported.

Labor unions and Democrats warned that the offer is not trustworthy. Some federal employees said they were heartened by Thursday's court ruling.

"It's a glimmer of hope that the courts might help us and block the whole resignation program," said an employee at the General Services Administration, which manages federal properties.

Meanwhile, the Trump White House is amid a dramatic downscaling of the US Agency for International Development, or USAID, which distributes humanitarian aid around the world.

The administration plans to keep only 294 staff members out of the agency's worldwide total of more than 10,000, including only 12 in the Africa Bureau and eight in the Asia Bureau, sources told Reuters on Thursday.

The largest US government workers' union and an association of foreign service workers sued the Trump administration on Thursday over cuts to USAID.

The lawsuit, filed in Washington, DC, federal court by the American Federation of Government Employees and the American Foreign Service Association, seeks an order blocking what it says are "unconstitutional and illegal actions" that have created a "global humanitarian crisis".

The Trump administration's effort to slash and reshape US foreign aid is crippling the intricate global system that aims to prevent and respond to famine.

Humanitarian organizations have hit roadblocks in getting paid for emergency food operations. Questions about which programs have permission to continue have gone unanswered because the people who normally field such inquiries — officials at USAID — have been placed on leave, sources said.

About 500,000 metric tons of food worth $340 million are in limbo, in transit or storage, as humanitarian organizations wait for US State Department approval to distribute it, said Marcia Wong, a former senior USAID official who has been briefed on the situation.

Agencies Via Xinhua