President Donald Trump has offered buyout packages to almost all federal workers who do not want to return to the office, a major move designed to shrink the US government.

In an email sent to millions of employees on Tuesday, his administration told workers they had to decide by 6 February whether they wanted to be part of a "deferred resignation program".

If they agreed to leave their jobs by that date, the message said, they would receive about eight months of salary as a severance package.

The Trump administration expects up to 10% of employees to accept the offer, or around 200,000 of the more than two million workers the federal government employs, according to the BBC's US partner CBS News.

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

Workers wishing to take the deal on Tuesday were asked to reply to the email with the word "resign" written into the subject line. The offer includes both pay and benefits for workers until 30 September.

Certain employees did not receive the offer, including postal workers, members of the military, immigration officials, and some national security workers, according to the email.

The message from the Office of Personnel Management, the government's HR agency, on Tuesday evening also warned of future downsizing that could impact those who choose 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 reads.

The email follows Trump's earlier announcement that federal employees who had been working remotely since the Covid pandemic would be required to return to the office five days a week.

Speaking to CNN on Tuesday, Stephen Miller, the White House deputy chief of staff for policy, said the government's two million workers were "overwhelmingly left of centre", adding it was "essential" for Trump to "get control of government".

Trump 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 the "Department of Government Efficiency" (Doge).

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

The mass buyout offer came at the end of an at-times chaotic day in Washington, following a memo Trump issued which said he would pause federal grants, loans and other assistance.

A district judge suspended the order - which was initially set to go into effect on Tuesday afternoon - until next Monday.

In the hours before that decision, there was widespread confusion over which federal programmes and organisations would be impacted. The White House repeatedly sought to assuage concerns that Social Security payments and Medicaid access could be disrupted.

In a letter to the White House, top Democrats expressed "extreme alarm" about the plan to pause funding.

Also on Tuesday, Trump signed an executive order aimed at restricting gender care for young people.

The order, titled 'Protecting Children from Chemical and Surgical Mutilation', says it will prevent those aged under 19 from making "life-altering" choices.

"It is the policy of the United States that it will not fund, sponsor, promote, assist, or support the so-called 'transition' of a child from one sex to another," the order says.

It is unclear, however, how the order would be implemented and it is likely to be challenged in court.