The Department of Homeland Security’s internal watchdog division has been so weakened under the Trump administration that it is failing to provide basic oversight of the government’s third-largest federal agency, according to whistleblowers and lawmakers from both parties.

DHS’s Office of the Inspector General is on pace to publish fewer than 40 audits and reports this fiscal year, the smallest number since 2003 and one-quarter of the agency’s output in 2016, when it published 143, records show. The audits and reports cover everything from contracts and spending to allegations of waste and misconduct.

At a time w hen DHS has morphed into an instrument for some of President Trump’s most ambitious domestic policies, the inspector general’s role calls for the office to exert rigorous oversight of the department’s $70 billion budget and 240,000 employees, Democratic and Republican lawmakers say.

But the agency’s authority and productivity have withered, and in the weeks before the coronavirus outbreak, Inspector General Joseph Cuffari ducked requests to appear on Capitol Hill for routine testimony, a decision congressional staffers describe as unprecedented.

Adding to the turmoil, the office’s second-in-command and former acting director, Jennifer Costello, was placed on administrative leave last month for alleged ethical violations, three current DHS officials said. An attorney for Costello said her client was not given a reason for her removal, but Costello believes she has been retaliated against for trying to denounce Cuffari’s mismanagement and wrongdoing.

Cuffari, who previously worked as an aide to former Arizona governor Jan Brewer (R), was confirmed unanimously by the Senate in July. He declined a request for an interview through the office’s spokeswoman, Erica Paulson.

Paulson declined to answer questions sent in writing, and she said Costello was not authorized to speak publicly about the inspector general’s office.

“The Office of Inspector General respectfully declines to comment,” Paulson wrote in an email.

The inspector general’s headquarters were often empty on weekdays long before the coronavirus outbreak sent some federal workers home, according to one frustrated senior staffer. He described coming to work in recent months and regularly finding the lights off because no one else was there.

Established in 2002 after the creation of DHS in the wake of the Sept. 11, 2001, terrorist attacks, the inspector general was tasked with providing “independent oversight and promote excellence, integrity, and accountability” within the department. While the inspector general reports to the DHS secretary, the agency is designed to work closely with congressional oversight committees to preserve independence.

Since October, the office has published 17 audits and reports, many of which are routine reviews of Federal Emergency Management Agency grants to states and municipalities. Lawmakers have also raised concerns about the quality as well as the quantity of the office’s work.

Rep. Bennie Thompson (D-Miss.), chairman of the House Homeland Security Committee, has joined other lawmakers pressing for Cuffari to explain what is happening at his agency.

“Particularly in these times, we need a DHS Inspector General who can and will be a vigilant and thorough watchdog,” he said in a statement to The Washington Post, noting that he has invited the inspector general to testify at a hearing later this month and expects him to appear, as all other previous inspectors general have. “It is deeply troubling that the office is not releasing reports at the rate it has done in the past, and that the work that is being released is not up to standard. This clearly cannot continue.”

Members of both parties have written to the inspector general to share their worries about chronic dysfunction. In a Dec. 6 letter, the top Republican and Democratic officials on the Senate and House homeland security committees wrote to Cuffari to raise “serious concern about the cumulative effect of long-standing management and operational challenges” at his office.

“Allegations have come to our attention that the office has been plagued by ongoing bureaucratic infighting and competing allegations of misconduct that threaten OIG’s ability to conduct effective oversight,” the lawmakers wrote, telling Cuffari that under his watch “problems have apparently persisted and in some cases worsened.”

The letter noted that morale at the inspector general’s office was low and slipping further, citing annual federal employee viewpoint surveys. It was signed by Thompson, as well as Sen. Ron Johnson (R-Wis.), chairman of the Senate Homeland Security and Governmental Affairs Committee; Sen. Gary Peters (Mich.), the committee’s ranking Democrat; and Rep. Mike D. Rogers (Ala.) the top GOP member on the House committee.

The lawmakers’ letter asked Cuffari to provide detailed records of his agency’s staffing levels, its recent hires, budget expenditures, employee complaints and other records for the past five years. Congressional staffers say Cuffari’s staff has provided partial responses.

In a Dec. 10 staff email obtained by The Post, Cuffari told agency employees that the office would fully comply with the request from lawmakers.

“I take the well-being of our workforce seriously and want you to know I am dedicated to improving our collective workplace experience,” Cuffari wrote. “It will take time and commitment from each of us, and I am confident we will get there, together.”

Cuffari told employees that he had hired a veteran federal prosecutor, Lynn Mattucci, as a special assistant, responsible for reducing backlogs and improving efficiency.

Congressional staffers and administration officials who spoke on the condition of anonymity because they were not authorized to discuss staffing at the inspector general’s office said Cuffari had gotten off to a slow start in part because he was blindsided by Costello’s move to fill several top positions before his takeover. The lawmakers told Cuffari in their letter that the hiring moves “deprived you of the opportunity to install lasting and coherent leadership” and might have contributed to budget shortfalls.

Costello, who served as acting inspector general before Cuffari was sworn in, had clashes with other senior staff, according to current and former DHS officials who spoke on the condition of anonymity because they were not authorized to publicly discuss staffing disputes. Paulson did not respond to questions about Costello’s status or her hiring decisions.

Eden Brown Gaines, a personal attorney for Costello, depicted her client as being a victim of dysfunction and retaliation. Costello has discussed whistleblower complaints with members of Congress, Brown Gaines said in a statement, and told lawmakers the inspector general had “suppressed a report concerning family separations at the border.”

Brown Gaines said Costello also denounced Cuffari for withholding reports and said he “made misrepresentations to Congress and mismanaged the budget.”

“Ms. Costello is a well-respected member of the IG community, having served for 20 years,” Brown Gaines said.

The DHS inspector general’s office has operated under a cloud in recent years amid various investigations of its conduct. On March 6, a federal grand jury in the District of Columbia indicted former inspector general Charles Edwards and an aide for allegedly conspiring to steal proprietary software and confidential databases from the government.

According to the allegations in the indictment, from October 2014 to April 2017, Edwards and his alleged co-conspirators tried to defraud the government by stealing software along with sensitive databases containing the personal information of DHS and Postal Service employees.

Last year, then-acting inspector general John V. Kelly retired after The Post reported he told staff to whitewash audits of the government’s response to disasters. Investigators found that Kelly praised the work ethic of federal emergency responders to show “FEMA at her best,” while instructing supervisors to focus on what the agency had done well, not its mistakes.