The State Department has struggled to recruit and promote women and minorities despite a nearly three-decade effort and lags behind the average for the federal government as a whole, according to a federal report released Tuesday.

The proportion of African Americans employed at State has declined over the years, though the overall number of racial and ethnic minorities has increased slightly, the report said.

The report, published by the Government Accountability Office, an independent federal watchdog, found a range of experiences among different groups.

Hispanics working for the government’s premier Cabinet agency rose from 5 percent to 7 percent of the workplace, while African Americans dropped from 17 percent to 15 percent.

Women and minorities were promoted to management and executive ranks at a lower rate than their white and male counterparts. The report, which analyzed a 16-year period beginning in 2002, said many factors could be at play.

Sen. Robert Menendez of New Jersey, the ranking Democrat on the Foreign Relations Committee, said he would introduce an act that would require the State Department to develop new recruitment, retention and promotion strategies.

“Something is wrong when most of those occupying our most powerful positions are overwhelmingly male and overwhelmingly pale,” he told reporters.

Secretary of State Mike Pompeo has spoken often about the need for more “geographic diversity” at the department and the importance of recruiting students “from the heartland.”

The State Department’s diversity problems go back decades, despite programs that aim to bring in more minorities. Diplomats and recruiters visit university campuses across the country, including historically black colleges as well as other schools with sizable minority enrollments. The State Department also has two programs, the Thomas R. Pickering Foreign Affairs Fellowship Program and the Charles B. Rangel International Affairs Program, that seek out job candidates from various ethnic, racial, gender, social and geographic backgrounds.

But progress has been spotty, as suggested by the title of the GAO report: “State Department: Additional Steps are Needed to Identify Potential Barriers to Diversity.”

The report notes that the increase in racial and ethnic minorities between 2002 and 2018 was entirely within the Foreign Service ranks of diplomats. In the same time period, the proportion of minorities in the Civil Service, which includes professional, technical and clerical staff, dipped slightly.

The decrease among African Americans has been most acute among women, dropping from 13 percent in 2002 to 9 percent in 2018. Again, the decline was centered on the Civil Service proportion of African American women. In the Foreign Service, there was an increase to 3 percent from 2 percent.

The GAO report said employees reported a widespread perception that it takes longer for women and minorities to be promoted at State. But there are indications that is changing. The report said a large difference in promotion rates for African Americans and whites in the entire period analyzed had disappeared after 2011.

The GAO report recommended that the State Department analyze its diversity efforts more closely to determine what barriers exist. The report said the State Department concurred with the recommendation, though the agency did not issue a statement immediately.