The word caucus probably derives from an Algonquin word caucasu, which refers to a (usually circular) meeting of chiefs of tribes, where no one person dominated.  (See the Webster's 1913 Edition dictionary.)

There is, of course, the use of "caucus" in American politics as a group-decision process (although that may have unfortunate associations for some folks!).  In fact, there was, in the long-ago days, an on-line "Dukakis Caucus" host that used the text-based version of Caucus.