WHEN the curtain opened on the 93rd Congress in January of 1973, the stage was set for battle. The usual spate of iournalistic previews unanimously warned of an impending clash between the Executive and Legislative branches, with the lines of battle extending to numerous fronts, but most notably the federal budget. The then reigning Nixon Administration assiduously cultivated this climate, first by means of leaks and official pronouncements and, as the year got underway, through a series of dramatic, deliberately provocative policy actions.