Ed Miliband has vowed to "fight for a fairer, more just, more equal Britain" and has urged Labour supporters to join him.
He said that despite what critics threw at him he 'was going nowhere.'
The Labour leader was speaking at the University of London in an attempt to to relaunch his party to the UK electorate.
Labour will fight the next election on a commitment to make Britain work "for everyday people", Ed Miliband is expected to say.
At a speech in London, Mr Miliband will contrast his approach with a Conservative party he says believes the UK's success "comes from a few at the top".
Despite recent poor polling, he will sound an optimistic note about next year's election, saying:
“We’re in a fight, but not because our opponents think we’re destined to lose. We are in a fight because they know we can win."
The deficit means Labour's approach will involve "big reform", rather than big public spending, he will argue.
Mr Miliband will also hit out at Ukip, saying Nigel Farage's party want to return the UK "to a more unequal, more unjust past".
He will say that his party will seek to address voters' concerns about immigration, but without trying to "out-Ukip Ukip".
Ed Miliband has declared he is the man to win the General Election, but will the Labour leader make the final whistle?
With less than six months to go until the General Election, what will Ed Miliband do today to turn around his party's fortunes?