The ban on members of the Lords working as lobbyists should be extended to the Commons, transparency campaigners have demanded.
SpinWatch argued parliament's efforts to restore public trust required that the ban should apply to both its houses, rather than just the lords.
Yesterday a group headed by Lord Eames published their new version of the Lords code of conduct.
They proposed forcing peers to sign an undertaking agreeing to abide by the code and recommended the establishment of a commissioner of standards ending centuries of self-regulation by the Lords.
Lord Eames also backed an outright ban on peers acting as "parliamentary consultants". It followed the first suspensions of two peers from the Lords for 350 years in the cash-for-amendments scandal.
SpinWatch believes MPs should be covered by the same ban on lobbying.
"It is obvious that the ban on parliamentarians acting as lobbyists must now extend to the House of Commons," David Miller, of SpinWatch, said.
"Public trust relies on knowing that MPs and Lords are acting in the public interest."
A recent report by the Commons' public administration select committee recommended a compulsory register of lobbyists, but it was rejected by the government last week.