Keir Starmer will warn that “things will get worse before they get better” as he urges voters to give his government time to repair the damage done by “14 years of populism and failure”.

The Prime Minister will make his first major speech since entering Number 10, telling the country that “things are worse than we ever imagined” before Labour’s landslide election victory in July.

He will draw a direct link between the last Tory government and the far-right parties that emerged earlier this summer, saying they are the result of the “cracks in our society” left by the Conservatives.

But he will insist that his government will, in time, turn things around and ensure that working people are “at the forefront of our minds and at the centre of everything we do”.

Starmer will say: “I said change wouldn’t happen overnight. If there’s rot deep at the heart of a structure, you can’t just cover it up.

“You can’t tinker with it or rely on quick fixes. You have to tackle the whole thing head on. Get to the root of it. Even if it’s harder work and takes more time.

“Because what else will happen? The rot will return. In the same places. And it will spread. Worse than before. You know that – and I know that. That’s why this project has always been about rebuilding the foundations of this country.”

The Prime Minister will add: “Things are worse than we ever imagined. In the first few weeks we discovered a £22 billion black hole in the public finances. And let no one say that this is performative or political.

“The (Office for Budget Responsibility) didn’t know about this. They wrote a letter saying that. They didn’t know – because the previous government hid it. Just last Wednesday we found out that the previous government had borrowed almost £5 billion more than the OBR had anticipated.

“We have inherited not just an economic black hole, but a societal black hole. And so we have to take action and do things differently. Part of that is being honest with people – about the choices we face. And how hard this is going to be.

“Honestly, it’s going to get worse before it gets better. I didn’t want to release prisoners early. I was chief prosecutor for five years, it goes against everything I’ve ever done. But honestly, if we hadn’t made that difficult decision right away, we wouldn’t have been able to respond to the riots the way we did.

“And if we don’t take tough action on all fronts, we won’t be able to rebuild the country’s foundations as we need to.”

The Labour Party is under fire for depriving 10 million pensioners of winter fuel payments, while the government is under pressure to abolish the cap on the two-child benefit introduced by the Conservative parties.

But Starmer will say: “I will not shy away from making unpopular decisions now if it is the right thing for the country in the long term. That is what a government of service means.

“This should not be a country where people have to be afraid to walk the streets or watch cars and buildings being set on fire.

“This shouldn’t be a country where the Prime Minister can’t guarantee prison places. But it also shouldn’t be a country where people are paying thousands of pounds more on their mortgages or waiting months for hospital appointments they desperately need.

“So when I talk about the legacy that the previous government left us – the £22 billion black hole in our finances – it’s not about lines on a graph, it’s about people’s lives. And the Tories are still not being honest about it. They haven’t acknowledged what they cost the country and they haven’t apologised for what they cost you.

“But I promise this — you will be the heart of our government, at the forefront of our minds and at the center of everything we do. That this government is for you, back in your service.”