campaigner

from WordNet (r) 3.0 (2006)

campaigner
    n 1: a politician who is running for public office [syn:
         {campaigner}, {candidate}, {nominee}]

from The Collaborative International Dictionary of English v.0.48

Campaigner \Cam*paign"er\, n.
   1. One who has served in an army in several campaigns; an old
      soldier; a veteran.
      [1913 Webster]

   2. one who is campaigning, especially a politician running
      for elective office, or one of his/her supporters.
      [PJC]