A powerful new survey of thousands of management-level federal employees found that the U.S. government is a massive bureaucracy that is under terrific stress, in part because managers feel they can’t get rid of underperforming employees, and often say their workers don’t have the skills they need to do their jobs.

Conducted by Vanderbilt University’s Center for the Study of Democratic Institutions, the survey polled 3,551 government officials, both career civil servants and political appointees. While some agencies received higher marks than others and most respondents said that believe they are equipped to perform at least their core functions, nearly one in five did not.

“The federal workforce is under stress and there are concerns emerging among federal executives about whether the workforce has the capacity and skills necessary to implement effectively the core tasks that they’ve been given by the president,” said David E. Lewis, a professor of political science at Vanderbilt and the lead researcher on the study.

Related: IRS Service This Tax Season Was ‘by Far the Worst’

“It’s time to do civil service reform,” he said. I worry that it will be done in piecemeal fashion in response to a crisis rather than the right way, which is to develop a modern-day human resources system for a modern government.”

Max Stier, president of the Partnership for Public Service, was at the downtown Washington venue where the report was released.

Stier, a longtime advocate of overhauling the federal personnel system said, “We unfortunately have all-too-little information about what is happening inside the federal government.” He described the data in the study as “really very valuable.”

Among the key insights from the study is what it reveals about the skills of the federal workforce. Asked if an “inadequately skilled workforce is a significant obstacle to [my agency] fulfilling its core mission, 39 percent of respondents agreed that it was. Only 45 percent of respondents disagreed with that statement.

Related: White House Claims Budget Victory, Blasts GOP in Review

To make matters worse, a plurality of respondents said that their agencies are unable to bring in the kind of talent they need. Asked to react to the statement “[My agency] is unable to recruit the best employees,” 42 percent agreed, while only 38 percent disagreed.

Managers complained about the Byzantine hiring process that new applicants must go through, and the restrictions that sharply limit eligible candidates to those fitting categories receiving special preference.

Remarkably, 40 percent of executives reported that within the past year another potential employer had approached them about leaving their current job. And the largest single source of attempts to poach federal employees was not private sector firms, lobbying firms, or government contractors. It was other federal agencies.

The study also found that an overwhelming majority of federal managers believe that it is extremely difficult, if not impossible, to reassign or fire employees who can’t or won’t do their jobs.

Related: The 10 Worst States for Taxes in 2015

When it comes to getting rid of non-management level workers who aren’t performing, a full 70 percent of respondents said that it “rarely or never” happens. It was seen as marginally easier to get a poor manager removed, with only 64 percent reporting that it never happens.

A particularly interesting finding in the study is that the managers who reported that they felt they had been well trained in the government’s employment policies also reported a greater success rate in removing unproductive employees. This suggests that the sheer complexity of the regulations governing the federal workforce makes it difficult for managers to make effective decisions.

The study also found that career civil servants were more likely than political appointees to report that they had been well-trained in government employment policies, and had a lower rate of complaints about the difficultly of firing unproductive workers.

“It’s a fascinating correlation,” said Stier of the Partnership for Public Service. “Political appointees really need to be trained better.”

Related: Democrats Call for Major Change in Social Security

Asked what it takes to move up in the ranks of government service, only 32 percent of respondents reported that promotions are guided by performance and ability alone. Fifty-four percent said that other factors were also considered, while 10 percent said performance and ability were not the main factors considered.

Despite their frustrations, though, large majorities of federal management-level employees say that they would recommend a career in public service to a young person. Among political appointees, 83 percent said they would recommend it, while 72 percent of career executives said the same.

Interestingly, the respondents who reported that performance and ability were the key drivers of promotion were also those most likely to recommend a career in government.