Just before the inauguration, Michael Horowitz, chairman of the Council of the Inspectors General on Integrity and Efficiency, was at a hockey game when he began getting calls from other inspectors general in federal agencies. The inspectors — independent officials who investigate waste, misconduct, mismanagement and criminal activity — were furious. Trump aides had let them know they might be replaced; for the first time ever, a president might fire them en masse.

The administration later backed down. But it has continued to undermine the inspectors’ role by failing to hire for open positions and planning to slash the offices’ budgets, one of the many ways the White House has found to diminish the oversight functions of the federal government.

Every major federal agency and program has an inspector general, a nonpartisan, independent official whose staff investigates cases of wasteful spending, criminal activity, employee misconduct and plain bad management. These are watchdogs with real teeth.

Mr. Horowitz, who is also the inspector general at the Department of Justice, recently told Congress that in fiscal 2015 alone, the offices identified $26 billion in potential savings and recovered an additional $10 billion through criminal and civil cases. That’s a return of $14 for every dollar in the offices’ budgets.