Nomination procedures vary from country to country and can be distinguished by a number of features, including, for example, the breadth of participation and centralization or decentralization of the process. At one end of the spectrum are processes that provide a broad opportunity for people to participate, such as primary elections in the U.S. and all-member party caucuses run by the major Canadian parties. Depending on which of these procedures is used, party leaders, a broader set of party officials, or a significant portion of party rank and file will play the gatekeeper role. Another consideration is to distinguish between systems that are patronage-oriented and those that are bureaucratic. In a bureaucratic system of candidate selection rules are detailed, explicit, standardized and followed regardless of who is in a position of power.
Authority is based on legalistic principles.
In a patronage-based system, there are far less likely to be clear rules, and even when they exist there is a distinct possibility that they are not carefully followed. Authority is based on either traditional or charismatic leadership, rather than legal-rational authority. Loyalty to those in power in the party is paramount. Aspirants track record in the party and in the constituency is the most widely valued characteristic in potential candidates. While these various systems emphasize different factors in choosing candidates, under any system an important consideration for parties is presenting candidates that the party believes will maximize their vote.