句子成分 one of the primary cause of the poor U.S.economic perfo

句子成分 one of the primary cause of the poor U.S.economic performance
Not long ago,with the country entering a recessing and Japan at its pre-bubble peak,the U.S.workforce was derided as poorly educated and one of the primary cause of the poor U.S.economic performance.
请问其中的：one of the primary cause of the poor U.S.economic performance 做什么成分?one指代的是什么?