Ed Miliband today launches his party on "the hard road back to power", saying it has to move beyond New Labour and commit to changes in policy and organisation as profound as those introduced by Tony Blair in 1994.

He also appears to clash with the shadow chancellor, Alan Johnson, by saying a 50p tax rate for those earning more than £150,000 should be permanent, as a way of creating greater equality in Britain. Making the country more equal, he says, is one of the issues that gets him out of bed in the morning. In his first full interview since becoming party leader, and marking his return to work after two weeks of paternity leave, he discloses:

• A commission on party organisation will be launched this weekend. It will examine the rules under which he was elected party leader, including the role of the unions.

• A policy review will be conducted including commissioned work by independent thinktanks and studies by each shadow cabinet member on the issues in their field. "In terms of policy, but not in terms of values, we start with a blank page," he says.

• The review is likely to include low pay, tough crime measures including asbos, and the "contributory principle" in the welfare state.

• His main priority next May will be the devolved and local elections and not the referendum on the alternative vote. He says the Liberal Democrats should change the referendum date if they really want to win.

• He will stand up for the "squeezed middle classes", a group he claims Cameron does not understand.

He warns his party not to expect a quiet life, saying: "I am talking about change as profound as the change New Labour brought because the world itself has changed massively, and we did not really change fundamentally as a party, or come to terms with the changes, and have not done so since 1994."

Miliband dismisses suggestions he has been too low-profile since becoming party leader, saying: "It's about digging in, and it's not about short-term fixes, nor shortcuts to success. There is a long, hard road for us to travel." He does not accept that the deficit is the product of over-spending by Labour, but says British politics has not come to terms with the 2008 banking crisis and the economy's over- exposure to financial services.

Rejecting calls for attention-seeking stunts, and referring to the Tories' failure to win an overall majority, he says: "I think David Cameron didn't win the last general election because he didn't undertake the profound change that I'm talking about for our party."

He also reveals he will spend time away from Westminster informally meeting people at work ranging from cleaners, small businessmen and bankers, in an attempt to understand more about their concerns.

Miliband says he does not want union levy payers disenfranchised from the Labour party elections, but is happy to look at how the relationship could be reformed. He also says the policy commission will look at the way in which a candidate recommended by a union's executive then has monopoly access to that union's membership.

He appears to disagree with Johnson, who has described the 50p top rate as only "right for now". Asked if the 50p rate was simply necessary to cut the deficit, Miliband says: "No, it's about statement about values and fairness and about the kind of society you believe in and it's important to me."

During his leadership campaign Miliband said a 50p top rate should be permanent and in his interview today says: "One of the things that gets me out of bed in the morning and that I care about is that Britain is a fundamentally unequal society and that's the reason I said what I said about the 50p rate."

He sticks with Labour's plan to halve, as oppose to eradicate, the deficit by the end of the parliament, insisting he will not concede that the Labour government overspent before the 2010 election.

"I don't agree with what the Tories say about us overspending. They are on a mission and we know what their mission is and we have got to take them on. Their mission is to say 'This deficit is not the result of an international banking crisis, it is the result of a crisis in government'."

He also rejects suggestions he has been shifting to the centre since becoming leader in September, arguing: "I said during the election I was the person who would take us beyond New Labour. That's the way I ran as a candidate and that is the way I am going to run the party. We've got to recognise that in terms of who we stand up for – we as New Labour lost touch of people's hopes and aspirations."

The overarching task, he says, is to examine "how you can create greater social justice in the economy without having to rely only on redistribution and the welfare state.

"What it is not about is saying we're going to aim for 112 policies by conference next year. Conference next year is about us saying 'we've gone out there and talked to people and they've told us what they think of their lives and politics and politicians'."

Labour, he says, "has got to be the best community organisation in the country".

On Nick Clegg, the deputy prime minister and Liberal Democrat leader, he says: "There are good and decent people in the Liberal Democrats – they are being led totally up the garden path I am afraid, and I think it is not in keeping with some of the good traditions of the Liberal party – Kennedy, Campbell and Ashdown.

"This is what I can't understand about Nick Clegg and the Lib Dems. They don't seem to get much out of their position in this coalition."