Tensions between federal watchdogs and the administration they monitor are not uncommon. But 11 inspectors general or their senior aides who served under Trump, many of whom spoke on the condition of anonymity to describe internal government deliberations, said hostility to oversight reached unprecedented levels during his time in office.

The result, they said, was that government hid wrongdoing from the public and important reforms to improve government efficiency were ignored. With Trump now out of office, advocates for government accountability predict other damaging revelations may only now begin to emerge.

“IGs under Trump faced an angry, account-settling president who had no compunction about removing those who threatened to reveal bad things about him,” said Gordon Heddell, a former inspector general at the Defense and Labor departments who served under Republican and Democratic presidents.