Robertson is a former Enron lobbyist and Clinton administration adviser who was hired by Fed Chairman Ben Bernanke this summer to help with congressional relations.
Washington's K Street is where many lobbyists, trade associations and law firms have their offices.
Grayson took exception to Robertson's role, saying she has criticized congressional efforts to increase oversight.
"Here I am the only member of Congress who actually worked as an economist, and this lobbyist, this K Street whore, is trying to teach me about economics," he said.
Alan Grayson, Economist