Which political party function involves parties seeking out "leaders" that will reflect their views? Which political party function involves parties seeking out "leaders" that will reflect their views?

The political party function involves parties seeking out "leaders" that will reflect their views is : Choosing a candidate

When choosing a candidate, the political party need to elect someone that would represent the aspirations of their voter base, otherwise the voters would started to take their support of them during the election.

This candidate would later on based their campaign on the promise to push for legislation that would benefit its voter base.