If Reince Priebus is, in fact, the chief of staff and operating as chief of staff, he is the most important staffer the president Donald Trump has. And it is not unusual for a president to set up some competing power centers, as Ronald Reagan did, but there`s nothing like being the chief of staff, which has so much say over what the president reads, who the president sees, who`s the last person the president talks to before he makes a decision.