Why is the process of nominating candidates considered to be the most important function political parties play in american government?

   Political parties have proven to be more successful than any other group in terms of nomination

Explanation:  Although other social groups participated in the nomination and appointment of candidates for office, they were not as successful as the political parties that have literally evolved in the business over time. With the expansion of the electorate and political parties were increasingly engaged in mobilising as large an army of voters as possible. In this way political parties have institutionalised themselves in order to carry out this very important, if not crucial and essential task, on which the influence and survival of the party depends at the end of the day.