The Collaborative International Dictionary of English v.0.48:

Logroller \Log"roll`er\, n.
   One who engages in logrolling. [Political cant, U. S.]
   [1913 Webster]

         The jobbers and logrollers will all be against it.
                                                  --The. Nation.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "logroller":
   Machiavellian, behind-the-scenes operator, eminence grise,
   finagler, five-percenter, fixer, four-percenter, gamesman,
   gray eminence, influence peddler, kingmaker, machinator, operator,
   pork-barrel politician, power broker, strategist, wheeler-dealer,
   wire-puller