Keir Starmer has said that the Autumn Budget will be "painful" as the country will have to "accept short term pain for long term good".
The prime minister delivered a speech in No.10's rose garden – symbolically chosen as a location that became synonymous with the previous government's "partygate" scandal.
"There is a budget coming in October, and it's going to be painful," said Starmer, in a speech designed to further emphasise the scale of the problems that the new Labour government claims it has inherited from 14 years of Conservative rule.
"We have no other choice given the situation that we're in."
In July, shortly after Labour won a historic landslide victory in the general election, chancellor Rachel Reeves accused the Conservatives of leaving a £22bn “black hole” in the public finances that she would have to repair through “difficult" decisions like scrapping unfinished infrastructure projects and restricting the winter fuel allowance for pensioners.
The PM described the decision to means test winter fuel payments as a "difficult trade off", but added that there will be "more to come" when the government sets out its economic agenda in October.
"I won't shy away from making unpopular decisions. Now, if it's the right thing for the country in the long term, that's what a government of service means."
In his speech, Starmer said the damage done to the country by the previous Tory government had made it harder for ministers and public services to respond to the recent riots.
The PM said people who rioted across the UK a few weeks ago had seen and "exploited" 14 years of Conservative "failure".
"That's what we've inherited: not just an economic black hole, a societal black hole," he said.
"And that's why we have to take action and do things differently, and part of that is being honest with people about the choices that we face, how tough this will be, and frankly, things will get worse before they get better."
Starmer said he was "shocked" when he discovered the full extent of the prisons crisis.
"It's going to take time to fix it... I can't build a prison by Saturday," he said.
He also referred back to his time as director of public prosecutions during the 2011 riots, but said that dealing with the disruption this summer had been "much harder" and had shown him "how far we have fallen" since.
"Back in 2011, I didn't doubt that the courts could do what they needed to do," he said.
"This time, to be honest with you, I genuinely didn't know. Let me tell you this: every day of that disorder, literally every day, we had to check the precise number of prison places and where those places were to make sure that we could arrest, charge, and prosecute people quickly. Not having enough prison places is about as fundamental a failure as you can get."
Starmer added that the riots did not "happen in a vacuum" and had exposed a "deeply unhealthy society".
Zoe Crowther is a reporter for CSW's sister title PoliticsHome, where this story first appeared