Sir Keir Starmer will say there is "light at the end of the tunnel" for the country in his first speech to the Labour Party conference as prime minister.
The PM will say "tough" decisions need to be taken now to "build a new Britain".
Conference hasn't gone to plan for the Prime Minister amid a scandal about political donations and anger among unions and many Labour members over the decision to cut winter fuel payments for millions of pensioners.
In his speech, Sir Keir will promise a future of "national renewal".
"The politics of national renewal are collective. They involve a shared struggle," he will say.
"A project that says, to everyone, this will be tough in the short term, but in the long term - it’s the right thing to do for our country.
"And we all benefit from that."
Sir Keir will say that "if we take tough long-term decisions now" there will be "light at the end of the tunnel".
However, he will warn against "easy answers" and offering "false hope".
The prime minister will also announce new legislation to crack down on welfare fraudsters, which Labour says is expected to save £1.6billion over the next five years.
Elsewhere in his speech, Sir Keir will commit to reducing net migration by training Britons to fill vacancies in the jobs market rather than allowing employers to rely on overseas labour.