Inner Circle

The term inner circle is used in reference to the small, close, intimate, exclusive, influential, and central figures involved in or part of an organization, activity, effort, or individual’s closest personal associates.

Example:

There are really only three people in the Senator’s inner circle who we needed to convince. They are all extremely close and if we can convince them then they can help us persuade the Senator to vote against the bill or at least step out of committee.