The Chief of Staff would probably be the person selected as having one of the greatest influences on the president in his administration. The Chief of Staff retains a very close relationship with the President and serves as a gatekeeper of information in regards to the information that is passed and the relationships that develop with other cabinet members. However, a strong argument could also be made for other important positions such as the National Security Advisor that is a major player in an administration. The amount of influence individuals have had in each of these positions has over time depended on the administration.
