The Obama administration’s budget chief warned Wednesday that threatened automatic budget cuts would have a devastating effect on the government, but he provided few details of the specific impact on federal workers and agencies at a congressional hearing.

In testimony before the House Armed Services Committee, Jeff Zients, acting director of the Office of Management and Budget, described areas of public safety that would suffer in the event of sequestration, including reductions in the number of FBI and Border Patrol agents, cuts to Federal Aviation Administration operations, and fewer food safety and workplace inspections.

Zients said all federal agencies will be ready to impose sequestration on Jan. 2 if no deficit agreement is reached to avoid the automatic cuts, but he did not provide specific details of the preparations. “We will be ready across the government if, unfortunately, Congress doesn’t do its job,” Zients said.

In sharp exchanges, Republican members laid responsibility for the budget crisis on the president while Zients blamed Republican intransigence.

In his testimony to the committee, Deputy Secretary of Defense Ashton B. Carter said the Pentagon would probably release temporary employees and impose a partial hiring freeze or unpaid furloughs in the event of sequestration.

But Carter said the Department of Defense does not want to “unnecessarily alarm our employees” by warning of possible personnel cuts, fearing it could introduce inefficiency and waste and harm military readiness.

The OMB announced earlier this week that spending cuts would not hurt uniformed military personnel.

Carter said sequestration “introduces senseless chaos” into the management of defense programs and warned that the cuts could create a “hollow” military force.

Military families and retirees could be hurt with cuts to support facilities, school construction, commissary and base housing, Carter added.