Rishi Sunak has claimed the current evidence suggests the Tories would suffer a defeat at the next general election under Liz Truss’ leadership.
The former chancellor also warned that going on a “huge borrowing spree” would only “make the situation worse” when it comes to inflation as the pair clashed again on tax.
It came as a new poll gave Ms Truss a commanding 24-point lead among the Tory membership, with 62 per cent of those surveyed backing the foreign secretary against Mr Sunak.
Just 48 per cent said that they could trust Mr Sunak, underlining the scale of the challenge he faces to win over the 160,000 members set to determine the next Prime Minister.
The poll of 723 members, carried out on Wednesday and Thursday, excluded those who answered don’t know from the lead given to Ms Truss. If they were included, 49 per cent intended to vote for Ms Truss compared to just 31 per cent for Mr Sunak.
Speaking to Andrew Marr on LBC, Mr Sunak said “all the polling evidence we have” points towards a defeat to Labour under Ms Truss.
“It’s pretty clear that I am the person that is best placed to defeat Keir Starmer in the next election,” he added.
Earlier, Ms Truss defended her tax cut plans costing at least £30 billion a year as “affordable” as the economic policies of both Tory candidates came under scrutiny.
While Mr Sunak has pledged to cut taxes, he has claimed that doing so now would exacerbate inflation.
He defended his planned rise in corporation tax, saying the increase was “perfectly reasonable”.
“What we are doing is actually combining that with some other reforms to make the system much more generous for the things that we know actually drive growth, and that’s businesses to actually invest,” he said.
“It’s all very well businesses making a profit, and that’s something fantastic that I support. But what I want them to do with that is to invest that in the economy. That’s how we help drive growth in this country.”
Ms Truss has in turn claimed that the Tories would be defeated by Sir Keir were Rishi Sunak to become Prime Minister as a result of the economic policies he imposed while in charge of the Treasury.
During a visit to a charity in Peterborough, Ms Truss vowed to continue with the Government’s planned spending on social care.
“We can afford it within our budgets. We didn’t have to do the national insurance rise,” she said in a veiled attack on Mr Sunak’s policy.
“It’s still the case that under my plans we can start paying back the debt within three years.”
Ms Truss has also pledged to scrap the scheduled corporation tax rise and suspend green levies on energy bills, insisting her economic plan was “not a gamble” despite experts warning it was fiscally irresponsible.
Robert Joyce, the deputy director of the Institute for Fiscal Studies (IFS) think tank, put Ms Truss’s tax cuts at “more than £30 billion per year - and possibly considerably more”.
The plans “mean higher borrowing or less public spending, or some combination”, he said, though their impact remains unclear because Ms Truss’s plans are “yet to be fleshed out”.
He said that, without spending reductions, the tax promises would “likely lead to the current fiscal rules being broken”.
Mr Sunak, who has put economic pragmatism at the heart of his leadership bid, said it would be easy to vow to “do this lovely sounding thing and this lovely sounding thing” but argued that making such promises would not be leadership.
“I think it would damage trust, because part of rebuilding trust is for the Government and politicians to deliver the things that they say, and sitting here promising you a bunch of things that I don’t think are right or deliverable would be wrong,” he said.
Both Mr Sunak and Ms Truss will take part in 12 hustings for the Tory members who will vote for their next leader, with the result being announced on September 5.
