Liz Truss has been unclear on the support she plans to offer Britons to help offset energy bills, if she's elected prime minister, as ITV News' Carl Dinnen reports.
A statement from Mr Sunak’s campaign said: “Following weeks of rejecting direct support payments as ‘handouts’, Truss supporters have slowly woken up to the reality of what winter brings.
"They now say that they will provide people with help – but what help, for who, when and how it will be paid for remains a mystery.
“The reality is that Truss cannot deliver a support package as well as come good on £50 billion worth of unfunded, permanent tax cuts in one go.
“To do so would mean increasing borrowing to historic and dangerous levels, putting the public finances in serious jeopardy and plunging the economy into an inflation spiral.”
The former chancellor’s team also seized on reports that Ms Truss is not planning to ask the independent Office for Budget Responsibility (OBR) for a forecast ahead of the emergency budget she is planning for next month.
Rishi Sunak's campaign team have called on Ms Truss to make clear what economic policies she would deliver on if elected prime minister.
“It’s no wonder they want to avoid independent scrutiny of the OBR in their emergency budget – they know you can’t do both and it’s time they came clean about that now,” Mr Sunak’s campaign said.
The criticism comes after Business Secretary, Kwasi Kwarteng - a close ally of Ms Truss - insisted, on Sunday, that "help is coming" in the face of rising energy bills.
Mr Kwarteng said work is happening across government to mitigate the worst effects of the gas crisis - but stopped short of saying how.
He added the key to energy security is producing it locally.
“I understand the deep anxiety this is causing. As winter approaches, millions of families will be concerned about how they are going make ends meet,” he wrote in the Mail+.
“But I want to reassure the British people that help is coming.”
He said Ms Truss “will look at what more can be done to help families” but insisted it is “entirely reasonable not to detail the exact shape of that support until she has all the information to hand.”
It comes after experts warned energy prices could spike at as much as £6,000 per year for the average household from next April.
Consultancy Auxilione predicted that the price cap on bills will gradually rise by more than £4,000 in the next eight months, with the cost-of-living crisis set to get worse between now and next summer.
They said that the cap is expected to reach £3,576 in October, rising to £4,799 in January, and finally hitting £6,089 in April.
That’s on top of an economy expected to head into a recession, according to Bank of England’s forecast, with inflation possibly peaking at 13%.
Kwasi Kwarteng has said it will be up to the new prime minister to decide how the government might help.
Ms Truss, however, has said there is “too much talk that there’s going to be a recession” as she insisted an economic slump is not inevitable.
The foreign secretary suggested a “level of ambition” was needed to “change the orthodoxy” and avoid the outcome forecast by the Bank of England.
The economy shrank by 0.6% in June and forecasters predicted it will contract again in the final quarter of this year and throughout 2023.
But Ms Truss reiterated her belief this can be averted as she pins her hopes on immediate tax cuts spurring growth of the economy, as inflation drives a cost-of-living emergency.
In an interview with the Sun on Sunday, she promised a “small business and self-employed revolution” to help turn things around.
“Those are the future big companies we need to develop — and why shouldn’t Britain have the next Google or the next Facebook? Why shouldn’t it be a British company?” she said.
“It’s about that level of ambition. There is too much talk that there’s going to be a recession. I don’t believe that’s inevitable. We can unleash opportunity here in Britain.”
Among Ms Truss’s economic plans is a review of IR35 rules, which she argues “treat the self-employed the same as big business” and can force self-employed workers to overpay tax.
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The rule was introduced in 2000 to prevent tax avoidance by “disguised employees” who do the same job as an employee but escape income tax and national insurance by providing services through an intermediary such as a personal services company.
High-profile TV personalities have been targeted under the rules.
Meanwhile, the Sun reported plans being drawn up by the Treasury for doctors to be able to write prescriptions to give people money off their energy bills.
Shadow health secretary Wes Streeting accused the Conservatives of having “lost the plot” with the proposal, as he reiterated Labour’s proposal to stop energy bills rising over the winter.