At the same time, GAO's work over the years, most prominently in our High-Risk and Performance and Accountability Series, has amply documented that many agencies suffer from a range of long-standing management challenges and a lack of attention to basic stewardship responsibilities,
It is well documented by the GAO that many agencies have problems with basic stewardship.  
mnli hypothesis: It is well documented by the GAO that many agencies have problems with basic stewardship.   premise: At the same time, GAO's work over the years, most prominently in our High-Risk and Performance and Accountability Series, has amply documented that many agencies suffer from a range of long-standing management challenges and a lack of attention to basic stewardship responsibilities,