The United States government is bracing for what is being called the largest mass resignation in its history, with more than 100,000 federal workers set to officially leave their posts on Tuesday. 

The departures come as part of the Trump administration’s “Deferred Resignation Program,” an initiative aimed at significantly reducing the federal workforce.

The timing is critical, with Congress facing a Tuesday deadline to approve further funding and avert a government shutdown. In anticipation of a potential stalemate, the White House has instructed federal agencies to prepare contingency plans for large-scale firings on top of the resignations.

Just eight days after President Trump’s second inauguration, the Office of Personnel Management sent an email message to nearly everyone in the federal workforce — more than 2 million people — laying out what it called the “Fork in the Road” program. Initially, employees had about a week to decide whether to resign, but in late March some federal agencies renewed the offer.

The program, one of several measures introduced by the Trump administration to cut the federal workforce, gave employees a choice: accept a buyout package or face the risk of future layoffs. The employees who accepted the offer left their positions immediately but were paid through September 30.

The director of the OPM, Scott Kupor, told one news radio station that the team that designed the buyout program — modeled on a deal that Elon Musk put together for employees at Twitter when he bought the social media platform — “did as much as they could to be appropriately generous and give people as long of a runway as they could to go transition into something new.”

According to a report from Senate Democrats in July, the program is projected to cost $14.8 billion, with 200,000 workers receiving full pay and benefits while on administrative leave for up to eight months.

The Trump administration says the program is a necessary step toward improving efficiency across the federal government. Officials at OPM argue that the one-time costs will lead to long-term savings.

In an August memo, Mr. Kupor said, “We designed the DRP as a practical, humane, and voluntary option to accelerate workforce transitions in a system that desperately needed movement … the government will save $20+ billion in costs annually.”

According to the White House, the total number of departures through various programs, attrition, and retirements is expected to reach about 275,000.