More supportive is Craig Laundy, minister for small business, who welcomed the energy policy, including the addition of the ACCC's recommendation.

"This is crucial for small and family businesses, because for some, energy costs are their single-most expensive cost input," he said. "Prices are coming down and businesses can look forward to them coming down further because of the action the government has already taken and will be taking as part of the [guarantee]."

The prospect of last-minute changes to the energy policy surprised state and territory governments who were already rushing to prepare submissions to their own cabinets by early next week ahead of next Friday's COAG gathering in Sydney.

Shane Rattenbury, the ACT's energy minister, wrote to Mr Frydenberg on Friday calling for details on any so-called "NEG-plus" policy so governments and the public "can assess it well in advance of any request for approval".

“I remain concerned that the [scheme], as it has been so far presented to state and territory ministers, does not accurately reflect the energy policy that the government will ultimately present to the Australian Parliament, or potentially impose on the Australian people", he said.

'No urgency'

Mr Kelly said any government underwriting of new power sources would affect the projected outcomes of the energy policy, and the MPs should be shown how modelled outputs are affected.

"I don't think there's any urgency to rush this through" the party room on Tuesday week, Mr Kelly said, adding "there's a fair bit of scepticism in the joint party room".

He said Labor jurisdictions should think twice about approving the policy because - at least according to the Energy Security Board projections - carbon emissions would start rising after the first few years of the scheme's implementation.

The Greens and environmental groups "will go ballistic if there's an increase in emissions", undermining Labor from the left, he said.

'Laser-like focus' on prices

A spokesman for Mr Frydenberg declined to comment on the "NEG-plus" plan, saying only the government had "a laser-like focus" on cutting household power bills.

“The [ACCC] report contains a comprehensive package of 56 recommendations spanning the entire electricity supply chain, which the government is carefully considering," he said.

The Labor-led Queensland government shared the ACT's worries about late changes to the plan.

"We are concerned about uncertainty around the final design of the National Energy Guarantee in light of increasing division within the Federal Coalition party room," said a spokeswoman for Energy Minister Anthony Lynham.

"State and territory ministers are being asked to sign off on a detailed design before it goes into a fractured party room and potentially emerges as a completely different animal."