The group is calling for a ‘mandatory public register of lobbyists, with full financial disclosure' - something that lobbyists are strongly opposed to.
Spinwatch's representatives were given more than an hour to persuade MPs of their case, but their arguments were met with fierce opposition by the majority of the committee.
Labour MP and committee chair Tony Wright told the witnesses: ‘You don't need regulation unless there's a problem.' Wright then repeatedly suggested he had not been convinced that there was a need for a ‘great elaborate regulatory system'.
Liberal Democrat Jenny Willot told the campaigners: ‘You might be overestimating the influence of lobbyists on MPs.'
And Conservative Charles Walker called the campaigners ‘conspiracy theorists'.
However the campaigners did get some support from the Labour MPs David Heyes and Kelvin Hopkins.
Spinwatch was represented by the academics William Dinan and David Miller. The select committee also heard from Peter Facey of Unlock Democracy, which incorporates the campaign group Charter 88.
The committee's next session on lobbying takes place on 31 January.