The proposals, announced earlier this month, which outline how the Act would be implemented have been met with concern by industry experts such as APPC chairman Iain Anderson and PRCA director-general Francis Ingham.
Phil Morcom, co-chair of the group, said: "The legislation does not address the major concerns about lobbying in the UK following high profile scandals and examples of people abusing positions of power and influence.
"The consultation shows a disregard for expert views from across the lobbying industry and is unlikely to result in an effective or fair system of regulation."
Morcom argued that had the Lobbying Act been in force this year, it would have restricted a range of referendum campaigning in Scotland.
He said: "The democratically inclusive electoral contest in Scotland resulted in increased voter registration and civic engagement – this could not have taken place if the Lobbying Act was in force.
"The vitality of the Scottish referendum campaign has been endorsed across the political spectrum and should be welcomed rather than curtailed. Now at a time when we want more people to engage with politics and democracy, we must be extremely wary of the Act's potential to push activity into the hands of the few, rather than the many."