An influential Commons committee is threatening to re-open an investigation into the prime minister's powers over ministerial behaviour, following David Cameron's refusal to sanction Jeremy Hunt.
The threat comes amid growing anger at the prime minister's failure to refer Jeremy Hunt to the independent adviser on ministerial interests, after an evidence session at the Leveson inquiry yesterday provided more evidence of apparent bias towards News Corp.
Bernard Jenkins, the Conservative chair of the Commons public administration committee (PASC), said his party leader's behaviour was further proof the rules around the code needed to be changed.
“PASC has previously made clear that the prime minister’s adviser on ministerial interests should not have to depend on a referral from the prime minister in order to determine whether or not there has been a breach of the ministerial code," he said.
"It is likely that that PASC consider this matter again when parliament resumes after the Whitsun recess.”
The threat to re-open an investigation into the rules around the ministerial code suggests there is a growing rebelliousness in parliament after the media secretary's damning evidence to the Leveson inquiry failed to prompt any action from Downing Street.
Under the current rules, only the prime minister can refer a minister to the independent adviser, unlike the commissioner for parliamentary standards, who can assess complaints about MPs if a member reports a concern.
The prime minister strengthened the ministerial code and the independent adviser when he came into Downing Street but stuck to the caveat that he would have to make referrals.
In the case of Mr Hunt, he is discouraged from referring the media secretary because any criticism would also reflect badly on his own judgement.
The PASC investigation would not trigger any change of the rules unless it was accepted by the government, but it would heap further embarrasment on Mr Cameron and provide Ed Miliband with more ammunition against the Tory leader.
Labour tried to sidestep the referral process this morning by demanding a Commons vote on whether Mr Hunt should be referred to the adviser.
"Jeremy Hunt has broken the ministerial code and misled parliament," shadow media secretary Harriet Harman said.
"It is not acceptable that these rules have been broken and we will call a vote insisting that Jeremy Hunt's breaches of the code are referred to the independent adviser on ministerial interests
"The ministerial code sets the standards which secretaries of state must live up to. When David Cameron came into power, he upgraded the code and he said he was going to have higher standards in public office. Today those words ring hollow - he has just torn up the code," she added.
"Even if David Cameron thinks it is acceptable for a minister to break the code he drew up, we do not and will call a vote."
Mr Hunt's behaviour constituted an "open and shut resignation offence", Ms Harman added.
Yesterday's testimony also threatened to drag George Osborne into the heart of the row, after details of his conversations with Mr Hunt were revealed.
On the day Vince Cable lost responsibility for the BSkyB bid for alleged bias, Mr Hunt received a phone call from James Murdoch.
Minutes after putting the phone down, he texted George Osborne: "Could we chat about Murdoch Sky bid? Am seriously worried we are going to screw this up."
The chancellor replied: "I hope you like our solution."
Within hours Mr Hunt was given responsibility for the bid.
The Leveson inquiry continues on Monday.