A federal judge on Friday called for a two-week pause in the Trump administration’s plans for mass layoffs and program closures, barring two dozen agencies from moving forward with the largest phase of the president’s downsizing efforts, which the judge said was illegal without congressional authorization.

Of all the lawsuits challenging President Trump’s vision to dramatically scale back the form and function of the federal government, this one is poised to have the broadest effect. Most of the agencies have yet to announce their downsizing plans, but employees across the government have been anxiously waiting for announcements that have been expected for weeks.

Ruling just hours after an emergency hearing on Friday, Judge Susan Illston of the Federal District Court for the Northern District of California said the government’s effort to lay off workers and shut down offices and programs created an urgent threat to scores of critical services.

Congress set up a specific process for the federal government to reorganize itself. The unions and organizations behind the lawsuit have argued that the president does not have the authority to make those decisions without the legislative branch.

Judge Illston noted that process requires consultation with Congress on any plan to abolish or transfer part of an agency.

“It is the prerogative of presidents to pursue new policy priorities and to imprint their stamp on the federal government,” she wrote in a 42-page order. “But to make large-scale overhauls of federal agencies, any president must enlist the help of his coequal branch and partner, the Congress.”