RISHI Sunak said he would not make promises he could not keep when it came to the cost of living crisis, as he stepped up his attack on Liz Truss’s plans for tax cuts, warning they would increase borrowing and fuel inflation.

He compared his approach to Margaret Thatcher’s, saying she was prepared to say things “that may have been difficult to hear, but were right for the country”.

The former chancellor has acknowledged he is the underdog in the race to become the next prime minister but insisted he was still in the contest and it was important the public had the chance to debate the “very clear difference” between the two candidates’ approaches.

The leadership hopeful told BBC ­Radio 4’s Today he was “very ­privileged and humbled” that ­supporters of Margaret Thatcher’s economic ­policies – including ­former chancellor Lord Lawson – were ­backing him.

He said of Thatcher: “She knew that you have to grip inflation – tax cuts funded by borrowing aren’t a sensible approach.

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“Actually, one thing I admire and respect about her – and I think many other Conservatives do as well – is she was prepared not just to say the easy things that people may have wanted to hear.

“She said the things that may have been difficult to hear, but were right for the country and had the courage of her convictions.

“And that’s the standard that I hold myself to. I don’t want to make promises that I can’t keep.

“And that’s why I believe my plans are the right ones for our nation.”

The leadership contest runs until September 5 and critics have complained it is dragging on for too long, leaving the country without an ­effective Government until then.

“When it’s over, I’m sure we can look back and reflect,” Sunak said.

“One thing is clear – there is a very clear difference of opinion in this leadership election.

“There is a difference of opinion in how you grip inflation and whether that’s a priority or not; there’s a difference of opinion about whether you prioritise – in my view – helping vulnerable people with the cost of living rather than giving tax cuts, funded by borrowing to very large companies and relatively wealthy people.

“Those are big differences, and it’s right that we have a debate about them because they are going to shape the course of our nation over the coming months and years.”

He said that any measures to alleviate the cost of living had to be affordable and not make inflation worse, because otherwise it would be a “gamble with people’s savings, with their pensions, with mortgage rates”.

But he declined to be drawn on whether he would revolt and vote against Truss’s emergency budget if she became prime minister.

Defence minister James Heappey, a supporter of Truss, said she was “in the business of cutting taxes”.

Asked on Times Radio ­whether people should be expecting to pay more in other taxes as a result of the Foreign Secretary’s pledge to reverse the rise in national insurance contributions, he said: “There’s definitely not any part of Liz’s body, as far as I can tell, that agrees with raising taxes.”

Truss used Tuesday night’s leadership hustings in Birmingham to reject criticism of her tax-cutting plans.

“This whole language of ­‘unfunded’ tax cuts implies the static model, the so-called abacus economics that the Treasury orthodoxy has promoted for years, but it hasn’t worked in our economy because what we have ­ended up with is high tax, high ­spending and low growth,” she said.

Meanwhile, Truss vowed to “turbocharge” the East Anglian economy, while Sunak set his sights on fixing failing mental health services, as the pair unveiled their respective visions for the region. Truss said she would unleash the private sector in the area with “tax cuts and better regulation”.

As part of his package of ­proposals for the region, Sunak pledged to ­order a review of controversial plans to run a 180km power line across East ­Anglia and Essex.

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Both shared their plans ahead of the penultimate Conservative ­leadership hustings tonight, which is due to take place in Norwich.

As the MP for South West ­Norfolk, Truss said she understands the ­challenges faced by the area.

Truss also pledged to tackle trade union strike action, such as that at the Port of Felixstowe this week.

She said her government would urge the trade unions to call off strike action, get around the negotiating ­table and agree a settlement with the port.

She said she would also cut EU red tape for farmers, reform Treasury ­investment rules, and scrap top-down housing targets.

Truss said: “I have been lucky enough to be the MP for an East Anglian seat for 12 years, and in that time I have gained a strong understanding of the region and its strengths, but also the challenges it faces.

“If elected prime minister, I will turbocharge the economies of places like Norwich, Great Yarmouth and across East Anglia by unleashing the private sector with tax cuts and better regulation, cracking down on strike action slowing our ­economy, and repealing the EU regulations that do not work for our rural ­communities.”