caucus vs fringe movement

caucus

verb
  • To meet and participate in a caucus. 

  • To bring into or treat in a caucus. 

noun
  • A political interest group by members of a legislative body. 

  • A usually preliminary meeting of party members to nominate candidates for public office or delegates to be sent a nominating convention, or to confer regarding policy. 

  • A grouping of all the members of a legislature from the same party. 

fringe movement

How often have the words caucus and fringe movement occurred in a corpus of books? (source: Google Ngram Viewer )