The State Department formally notified employees on Thursday that it was about to begin layoffs as part of a consolidation plan that department officials say will reduce bureaucratic bloat but that critics call a shortsighted blow to American diplomacy.

In an internal message sent to State Department workers on Thursday, Michael J. Rigas, the deputy secretary of state for management and resources, said the department would “soon” begin notifying U.S. employees who are losing their jobs.

Diplomats said that senior department officials had told them to expect layoff notices as soon as Friday morning.

The layoffs are part of a reorganization plan unveiled in May by Secretary of State Marco Rubio, who called his department “bloated” and stifled by bureaucracy. Mr. Rubio said the changes would better align it with core American values and root out pockets of “radical political ideology.”

The State Department is proceeding with the cuts two days after the Supreme Court overturned a lower-court order that had blocked the Trump administration from implementing mass layoffs across the federal government.

The union that represents trained diplomats who rotate overseas, called Foreign Service officers, expects about 700 of those based in the United States to lose their jobs. A larger number of civil service workers, who work mostly in Washington, are also expected to be fired, in what is officially known as reduction-in-force actions.