Representatives of Spinwatch and Unlock Democracy appeared before the committee last week and pressed the case for tougher regulation. But CIPR immediate past president Lionel Zetter claimed the campaigners failed to make a strong enough argument.
'Most members of the committee seemed to feel that the type of elaborate regulatory regime that they are advocating would be inappropriate and unnecessary in the UK,' he said.
The campaigners had argued for a system of compulsory regulation similar to that introduced in the US.
Spinwatch's David Miller told the MPs: 'It's clear that it is the democratic right of every interest in society to be able to access decision-makers and petition them, but it's also clear that in a democracy there ought to be some sort of level playing field.'
His colleague and fellow academic William Dinan said: 'The public have a right to know who is trying to influence policy.'
But the campaigners often struggled to come up with instances of underhand or inappropriate behaviour by lobbyists. 'I'm conscious that I've not given you evidence that you want,' Miller told the inquiry at one point.
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'. He also said it was not possible to 'read across the problems in one political culture to another'.
Labour MP Julie Morgan said: 'There's a real danger that you're stifling democracy with these suggestions.'
And Liberal Democrat Jenny Willot told the campaigners: 'You might be over-estimating the influence of lobbyists on MPs.'
Perhaps the most scathing attack came from Conservative Charles Walker, who said: 'You're creating a concern that simply doesn't exist.
He concluded: 'You're conspiracy theorists... You think there's a conspiracy on behalf of big business to corrupt democratic systems.'
However, the campaigners did get some support from Labour MPs Kelvin Hopkins and David Heyes.