caucus vs special interest

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. 

verb
  • To meet and participate in a caucus. 

  • To bring into or treat in a caucus. 

special interest

noun
  • A shadowy group with political power. 

  • A topic of particular interest and passion, particularly for an autistic person. 

  • Used other than figuratively or idiomatically: see special, interest. 

  • A particular political issue that is the focus of political advocacy. 

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