New guidance from the Trump administration out Wednesday will officially end the federal hiring freeze implemented days after the president took office.

“This does not mean that the agencies will be free to hire willy-nilly,” Office of Management and Budget Director Mick Mulvaney told reporters ahead of the formal release.

Instead, agencies are instructed to act wherever possible to bring their workforce size and activities in line with Trump’s fiscal 2018 budget plan, which called for deep cuts to nearly every corner of the government and elimination of numerous programs.

Of course, the president’s budget request is merely a proposal, and it is congressional appropriators who will do much of the heavy lifting when it comes to how the government spends its money.

By the end of June, agencies are directed to report to OMB with a draft of their long-term restructuring plans and the status of their “progress on near-term workforce reduction actions,” according to the guidance.

Mulvaney insisted the federal restructuring is about “good government,” rather than big or small government, but he acknowledged that the plans would likely result in a net shrinking of the executive branch.

A former congressman from South Carolina, Mulvaney also noted the need for “congressional buy-in,” given that much of the restructuring would eventually flow through the annual budget and appropriations process, which is the prerogative of Congress.

“You just can’t wave a magic wand in the Oval Office and do these things,” he said.

But persuading lawmakers to sign off on a dramatic restructuring of government would be a monumental challenge.

And talk of shrinking agencies, cutting programs and laying off workers is sure to provoke strong protests from federal employee unions, local communities whose economies rely on government jobs including the D.C. metropolitan area, interest groups of all stripes and more.

Congressional outreach has not yet begun, Mulvaney said, though lawmakers were generally aware that action toward overhauling the bureaucracy was coming.

Mulvaney cited the EPA as the most prominent example of an agency likely to see a large reduction in its workforce under a potential executive branch overhaul.

On the other hand, the Department of Veterans Affairs and the Pentagon would likely grow under the restructuring plans, he added.

The Wednesday morning guidance calls on agency heads to take “immediate actions to achieve near-term workforce reductions and cost savings,” according to the written memorandum from the White House Office of Management and Budget.

Agencies are instructed to begin drafting plans to restructure their operations to end outdated, duplicative or inefficient programs, with input from the public.

— Niels Lesniewski contributed to this report.