ABSTRACT
Arriving at political decisions involves complex processes that vary according to the issues, the circumstances at the time the decisions are being taken, and many other institutional and personal factors. Three major sources can be determined from which the eventual solutions to problems are generated: the institutional machinery of government itself, the party system and interested groups. Most decisions will involve all three of these structures in some degree or another, but as we have already seen the role of political parties in terms of policy formation is relatively weak, and a vacuum is created to be filled by the complex structure of interest groups. This separation of the functions of selecting leaders, and of initiating and influencing policy, gives to the American political system its peculiar flavour and complexity, which will become fully apparent only when we look at the behaviour of congressmen and senators and their relationship with the President and his administration. Party politics and pressure politics criss-cross and merge together to produce an ever-changing pattern of legislative and executive behaviour.
