Kemi Badenoch said she will tell “hard truths” to both the country and her party as she began her first full day as Conservative leader.
In her first media appearance since winning the Tory leadership election, Ms Badenoch said the UK is getting poorer and older and being “outcompeted” by other countries.
She told the BBC’s Sunday with Laura Kuenssberg programme: “We need to look at how we can reorganise our economy to be fit for the future, not just doing what we always used to.
“And I think that there is an exciting challenge there. I’m very optimistic about what we can do.
“But simply just saying things and making promises to the whole country without knowing how you’re going to deliver them, as we did on Brexit, as we did on net zero, I don’t think is building trust.”
In a speech following her victory over Robert Jenrick on Saturday, Ms Badenoch said the Conservatives need to be “honest” about the mistakes they made in government, but on Sunday she declined to be drawn into a “post-mortem” examination of each of her predecessors.
She did, however, argue that the previous government had raised taxes and borrowing too high, while also insisting that reversing this would not mean cutting public services.
She said: “I think the tax burden was too high under the Conservatives.
“That doesn’t mean that we have to cut public services, it means that we have to look at how we are delivering public services, and a lot of what government does is not even public services.”
Asked about specific taxes, she committed to reversing Labour’s decision to impose VAT on private schools if she came to power, describing it as a “tax on aspiration” that would not raise money.
When it was suggested that this would involve taking money from state schools, she said: “At the moment, certainly up until Labour came in, we didn’t have this tax, so it’s not taking money away from state schools.”
But Ms Badenoch was less willing to be drawn on whether she would reverse the increase in employers’ national insurance contributions if it meant taking money away from the NHS.
She said: “I don’t accept the premise of that question. We (the Conservatives) didn’t do those things in order to increase funding for the NHS, so it’s not a binary suggestion that if you don’t do this then that means less money for the NHS.”
Arguing that the tax rise is “not coherent” economically, she conceded that, with just 121 MPs, the Conservatives are “not going to be able to oppose anything in terms of getting legislation through”.
She added: “What we can do is make the argument about why we think what they’re doing is wrong, and I am making that argument that raising taxes in this way, whether it’s employer NI or elsewhere, is not going to grow our economy.”
Published: by Radio NewsHub