The Collaborative International Dictionary of English v.0.48:

Lobby \Lob"by\, v. i. [imp. & p. p. Lobbied; p. pr. & vb. n.
   Lobbying.]
   To address or solicit members of a legislative body in the
   lobby or elsewhere, with the purpose to influence their
   votes; in an extended sense, to try to influence
   decision-makers in any circumstance. [U.S.] --Bartlett.
   [1913 Webster]