Shadow Cabinet Office minister Nick Hurd put in a robust performance during last week's House of Commons debate on access and influence in Whitehall.
Amid MPs' concern about the lack of transparency in lobbying, Hurd said the Government was not being tough enough on the public affairs industry.
He said: 'I get no sense ... about a big stick being waved in the direction of the industry and no sense of urgency.'
The industry is keen to show ministers that it can achieve greater transparency without the need for statutory regulation. But the shadow minister's comments left observers in little doubt that the Tories are considering the statutory route.
Hurd expressed strong doubts about the ability of the public affairs industry to regulate itself.
He said he agreed that 'the current system of self-regulation is not effective' and suggested this was because industry-wide bodies - such as the APPC, CIPR and PRCA - were ill-suited to the job.
Hurd said the three bodies struggled 'to combine the role of being effectively a trade association that is dependent on members and a regulator of those members'. He insisted: 'That dynamic and tension is unsustainable.'
Responding to Hurd, Cabinet Office minister Angela Smith was lukewarm about penalising the public affairs industry should it fail to achieve transparency across the board.
She said: 'I sometimes prefer a carrot to a stick, but both can be employed when required ... The lobbying industry is aware that I am keeping a very close eye on the progress it is making in respect of establishing the council and a publicly available register of lobbying activity.'
Smith was due to discuss the issue with Sir Philip Mawer, an adviser to the Prime Minister, this week. She said: 'It is really helpful if all organisations declare all their clients. It is very helpful to have universality ... Those are the kind of issues that I will discuss with Sir Philip Mawer.'