BOSTON/WASHINGTON — Tens of thousands of US civil servants were cleared to take a buyout from Donald Trump's administration on Wednesday after a federal judge ruled the unprecedented downsizing effort could proceed.

About 75,000 workers have signed up for the buyout, revealed a spokesperson for the US Office of Personnel Management, which is equal to 3 percent of the civilian workforce. Trump's administration has promised to pay their salaries through October without requiring them to work, though unions have warned the offer is not trustworthy.

Unions representing federal workers had sued to stop the program and had delayed it for six days, while US District Judge George O'Toole in Boston considered the issue. However, the judge ruled on Wednesday that the unions did not have legal standing to bring the lawsuit and said the issue needed to be tackled in other forums before landing in court.

The administration said the program is now closed to new applicants.

"There is no longer any doubt: the Deferred Resignation Program was both legal and a valuable option for federal employees," the Office of Personnel Management said.

Unions involved in the dispute did not immediately say whether they would appeal the judge's decision or pursue other options.

"Today's ruling is a setback in the fight for dignity and fairness for public servants. But it's not the end of that fight," said Everett Kelley, president of the American Federation of Government Employees, which represents 800,000 federal workers.

The buyout is one of many approaches Trump is taking to slash a civilian workforce of 2.3 million that he has blasted as ineffective and biased against him. He has also ordered government agencies to prepare for wide-ranging job cuts, and several have already begun to lay off recent hires who lack full job security.

Trump's offer to pay salaries and benefits until October may not be ironclad. Current spending laws expire on March 14, and there is no guarantee that salaries will be funded beyond that point.

Lawyers with the US Department of Justice described the initiative as a "humane off-ramp" for those frustrated by Trump's broader plans to reduce the size of the workforce and end the ability of many to work from home.

Unions representing federal employees argued in their lawsuit that the program was "stunningly arbitrary" and violated a law that prevents agencies from spending more money than approved by Congress.

They warned the buyout, which does not apply to border guards, air traffic controllers and some other workers, could arbitrarily thin the workforce and disrupt vital government services.

Agencies Via Xinhua