lobbyist
noun [ C ]
GOVERNMENT uk/ˈlɒbiɪst/ us/ˈlɑːbi-/someone who lobbies people in positions of authority:
a lobbyist for sth Rutherford went to work as a consultant and lobbyist for the oil business.
the chief lobbyist for Harvard University
a company/industry/union lobbyist He is an industry lobbyist and former congressman.