One reason why interest groups form and grow strong is the relative
             weakness of American political parties. This weakness is due, in turn, to
             the separation of the three branches of government. Every legislator must
             summon a winning coalition in his or her own state or district and the
             coalition is not the same as the majority coalitions of successful
             assemblies. Splintered party loyalties thus enhance the influence of
             interest groups (Hays) - during election when financial support becomes
             critical and after election when the winning candidate gets closely
             Another reason is the decentralization of political power to states
             and localities, called federalism or federal system. This conduces to the
             growth of interest groups, which begins from the state or local level and
             which, as a consequence of the social and economic diversity, further
             weakens the party system. Furthermore, the independence of the judiciary
             encourages the expansion and strength of interest groups on issues not
             under the control of legislature or bureaucracy (Hays). These groups can,
             thus, use this clout to achieve policy objectives through the judiciary if
             they cannot do so by legislative action.
             And a third reason is public airing of an unlimited range of views
             and the freedom of the press and assembly. The various media have also been
             decentralized and this has made it more difficult to pay real attention to
             these groups. Only the internet has made access to these views easier. But
             these traditional realities, in general, provide the momentum and venue for
             the formation and power of such groups.
             The three major types of interest groups are business, labor and
             agriculture. Agricultural interest groups have waned because of the decline
             in the number of farmers in the USA (Hays). Major corporations are also
             major players in the economy, for which elected officials are held
             accountable. This w...