The Department of Homeland Security needs to address “gaps and weaknesses” in its mammoth effort to restructure the federal government to prevent a terrorist attack, according to a report from the Government Accountability Office.

The department, created after the Sept. 11, 2001, attacks, is the third-largest agency in the federal government, with more than 200,000 employees and an annual budget of more than $50 billion.

The report is to be released Wednesday at a hearing before the Senate Committee on Homeland Security and Governmental Affairs. The Washington Post obtained an advance copy.

“Eight years after its creation and 10 years after September 11, 2001, DHS has indeed made significant strides in protecting the nation, but has yet to reach its full potential,” says the report, which credits the DHS with “noteworthy accomplishments.”

Management problems have contributed to schedule delays, cost increases and performance problems in major programs, the report says.

One example cited is the Coast Guard’s Deepwater Program to modernize ships and aircraft, which has faced problems because the DHS lacks skilled personnel in fields such as acquisition management.

The DHS also needs to improve information-sharing with other federal agencies about cyber-based threats, the report says.

“The department has more to do to ensure that it conducts its missions efficiently and effectively, while simultaneously preparing to address future challenges that face the department and the nation,” Eugene Dodaro, the GAO’s comptroller general, said in prepared remarks. He also said that addressing the issues will probably be “particularly challenging” with budget cuts looming.

The report credits the department with important advances in its eight years, including the creation of a quadrennial homeland security review to provide a framework for government efforts, and the assumption of security screening responsibilities at airports nationwide.

Staff writer Joe Davidson contributed to this report.