The Collaborative International Dictionary of English v.0.48:

Heeler \Heel"er\, n.
   1. A cock that strikes well with his heels or spurs.
      [1913 Webster]

   2. A dependent and subservient hanger-on of a political
      patron. [Political Cant, U. S.]
      [1913 Webster]

            The army of hungry heelers who do their bidding.
                                                  --The Century.
      [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "heeler":
   Conservative, Democrat, Labourite, Republican, Tory, Whig,
   adherent, appendage, dangler, dependent, follower, hanger-on,
   hatchet man, henchman, loyalist, man, partisan, party faithful,
   party hack, party man, party member, party wheelhorse,
   registered Democrat, registered Republican, regular, retainer,
   satellite, servant, shadow, stalwart, tagtail, ward heeler,
   wheelhorse