It also says anyone who decides to quit will be exempt for the remainder of their contracts from Trump’s requirement that they work in the office rather than at home.

Senior Trump officials told US media that the plan could save the government up to $100bn (£80bn).

Delivering the offer, a message from the OPM, the government’s HR agency, highlighted planned reforms including a requirement that most employees work in their offices five days a week.

Since returning to the White House last week, Trump has already declared the end of Covid-era home working practices.

The OPM said the offer was available to “all full-time federal employees” – excluding certain staff such as postal workers, members of the military, immigration officials, and some national security teams.

Workers wishing to take the deal were asked to reply to the email with the word “resign” in the subject line. The offer has been described as “very generous” by the White House.

The message also warned of future downsizing that could impact those who chose to stay. “We cannot give you full assurance regarding the certainty of your position or agency but should your position be eliminated you will be treated with dignity,” it read.

Stephen Miller, the White House deputy chief of staff for policy, told CNN that federal workers were “overwhelmingly left of centre”, and that it was “essential” for Trump to “get control of government”.

The move has been condemned. In a statement to US media, the head of the American Federation of Government Employees (AFGE) union warned that this “purging” process would have “vast, unintended consequences that will cause chaos for the Americans who depend on a functioning federal government”.

Democratic Senator Tim Kaine was among those questioning Trump’s power to make such deals. “If you accept that offer and resign, he’ll stiff you just like he stiffed contractors,” he said. “He doesn’t have any authority to do this. Do not be fooled by this guy.”

The returning US president repeatedly pledged to cut the size of the government and slash federal spending while on the campaign trail.

He tasked Elon Musk and Vivek Ramaswamy with leading an advisory body focused on cutting regulations, spending, and headcounts within the federal government. Ramaswamy has since left this new Department of Government Efficiency (Doge) to run for governor of Ohio.

But the email on Tuesday bore resemblance to one sent to employees of Twitter, now X, in late 2022 after Musk bought the social media platform. He asked for an emailed response if they wanted to remain at the company.