The Tories need to be bolder in defending tax cuts for the rich, one of the frontrunners to be the next chancellor said.
Liz Truss, an ally of Boris Johnson, said the Conservatives should make the case for people earning £60,000 to be given a tax break.
The current Treasury Chief Secretary acknowledged she was “not yet at Number 11” but joked about her ambitions for the role.
Current Chancellor Philip Hammond is expected to be sacked by Mr Johnson if he wins the Tory leadership race and becomes prime minister, with Ms Truss or Sajid Javid likely to replace him.
Mr Johnson has put forward plans for a package of tax cuts, including for people earning more than £50,000.
The move led to a clash with Jeremy Hunt in the televised debate, with the Foreign Secretary claiming it was sending a signal that the Tories are “a party of the rich”.
But Ms Truss said: “The reason that Boris is getting flak for this is that the Conservative Party haven’t been prepared to make these arguments for at least a decade.”
At a Westminster lunch Ms Truss, who said Margaret Thatcher’s tax-cutting chancellor Lord Lawson was her favourite occupant of Number 11, defended Mr Johnson’s plans.
“If people feel, on an income of £55,000 that they have entered the higher rate tax band and that’s not fair, then that’s a problem and it can stop people wanting to aspire to earn more and be more successful,” she said.
Mr Johnson’s proposal was part of a package and the Government had already cut income tax for lower earners, she said.
“If we are never, ever prepared to say we are going to cut taxes for people on earnings of £60,000 I think that’s a problem,” she said.
“You have to look at the tax system as a whole.”
Ms Truss said the current overall tax burden on the economy was too high and suggested cutting stamp duty and reforming capital allowances for firms.
“Simplifying the tax system, making it clearer, more transparent, will improve revenues and improve economic growth,” she said.
“The big problem we have faced over the last nine years is our growth levels haven’t been high enough.
“We need to do everything we can to get those growth levels up, whether it’s issues of red tape on business, issues of too high taxation, opening up new trade opportunities – we need to go for growth.”
Ms Truss has made little secret of her ambition to become the UK’s first female chancellor.
She suggested that arch-Brexiteer Jacob Rees-Mogg was being touted to replace her as chief secretary, the second most senior minister at the Treasury.
“As outgoing chief secretary, I leave the public finances in good shape – the deficit is now down to 1%, the lowest since 2002. Much better shape than when (Labour’s) Liam Byrne left his infamous note saying ‘there’s no money left’.
“My note will be different. It will say ‘Jacob, if you need anything, I’ll be just down the hall’.”
She said no promises had been made about jobs, and it would be “presumptuous” because the leadership race had not concluded, but she wanted to be “in the engine room of the British economy”.
Shadow chancellor John McDonnell said: “This is back to the 1980s from Liz Truss and the Tories, with tax cuts for the rich and increasing inequality.
“It’s hard to believe that they haven’t learned the lessons of nearly a decade of Tory austerity.”