Labour cannot go into the next general election on a promise to reverse coalition cuts and return to the high public spending and redistribution of the Brown era, Ed Miliband says.
Instead of redistribution of income through measures such as Gordon Brown's tax credit programme, a future Labour government will have to focus on "predistribution", by doing more to ensure that work pays for the disadvantaged in society, Mr Miliband said.
In an interview with the New Statesman magazine, the Labour leader said that he accepted the "absolute reality" that government must now function in a more constrained fiscal environment than in the period of the Blair and Brown administrations.
It would be "politically crackers" for him to tell voters that he would be able to spend in the same way his Labour predecessors did or to promise to reverse coalition cuts to benefits such as the Education Maintenance Allowance (EMA).
Mr Miliband said that he and shadow chancellor Ed Balls sent out an "important" message earlier this year when they said Labour would be disciplined on tax and spending.
And he told the New Statesman: "Our position hasn't changed. Look, we absolutely hold to everything we said at the beginning of the year, and what Ed and I said was that the next Labour government is going to take over in very different circumstances and is going to have to have a very different prospectus than the last.
"And if we came along and said 'Look, we can just carry on like the last Labour government did' - I mean it's politically crackers to do that, because we wouldn't win the election and we wouldn't deserve to win the election.
"We can't say: 'Look, we just want to sort of carry on where we left off, you know, the electorate was wrong, we were right, thanks very much...' It's not realistic.
"Ed Balls is not going to go to the Labour Party conference and say: 'It's going to be the old model where we have economic growth and then we'll use lots of that money to spend lots, to spend billions of pounds.' It's not realistic and it's not credible."
While redistribution of income from the rich to the poor is "still necessary and will remain a key aim", Mr Miliband said Labour would put more focus on making work pay in the first place.