A consultation on changes to the way poverty is measured will be announced by Iain Duncan Smith today as the latest sets of official statistics are published.
The Work and Pensions Secretary will insist the Government remains committed to a Labour target - enshrined in law - to eliminate child poverty by 2020.
But with new figures tipped to show an interim aim of halving it by 2010 has been missed, he will say the present income-based measure wrongly encouraged Labour to massively increase state help.
Defending efforts to slash billions from benefits, he will call for experts to come forward with other factors to be considered in deciding how many young people are below the breadline.
And he will present figures suggesting the "vast majority" will be pulled out of poverty thanks to the new Universal Benefit if at least one parent works 35 hours a week at the minimum wage.
The figure would be 24 hours a week for a lone parent.
A series of recent reports from charities have warned steep cuts to benefit payments will dramatically increase the number of young people growing up in poor households.
Coalition figures including David Cameron and Nick Clegg however complain that the effects of other policies aimed at improving young people's life chances are not registered in the figures.
At present, the definition of poverty is a family on less than 60% of the median income.
The move came under fire from Labour, shadow work and pensions secretary Liam Byrne saying it meant "parents and their children will now be abandoned and told, 'you are on your own'".
But Mr Duncan Smith will accuse Labour of skewing the figures by massively increasing state support to families - without regard to whether it actually changed lives for the better.
"The Institute for Fiscal Studies have been clear that the previous Government are likely to have missed their target to halve child poverty by 2010 - we will find out for certain today," he will say.
"When we do, it will be critical to ask the following question: why didn't all the money have the impact it was supposed to?
"I believe the problem lies to a large extent in the common discourse around child poverty - which, in recent years, has become overwhelmingly focused on relative income.
"Of course money is important and will always play a part in future measurements of poverty. But increased income from welfare transfers is temporary if nothing changes."
Examples were drug-addicted parents who could spend the extra pound that technically took them out of poverty on another fix, he will suggest, or a long-term workless family pushed into welfare dependency rather than being pushed towards finding work.
Setting out his proposed changes, he will say: "We remain committed to the targets set out in the Child Poverty Act but it is increasingly clear that poverty is not about income alone.
"Today, I am pleased to announce that the Government is very interested in developing better measurements of child poverty, which include income but do more to reflect the reality of child poverty in the UK today.
"We will be seeking a wide range of views in the autumn as part of a green paper consultation on how best to measure child poverty.
"This is not an easy task and we will need help from experts in the field. But it is vital work, for unless we find a way of properly measuring changes to children's life chances, rather than the present measurement of income alone, we risk repeating the failures of the past."
Labour produced a series of previous quotes made by the Prime Minister and other senior Conservatives defending the relative poverty measure.
Mr Byrne said: "In a great country like Britain we should stand behind parents fighting to bring up their children free of the curse of poverty.
"Behind Cameron's promises we learn today that those parents and their children will now be abandoned and told, 'you are on your own.'"
Mr Duncan Smith told BBC Radio 4's Today programme: "What I'm talking about is getting away from a system that got so trapped in the idea of meeting a relative income target so narrowly that more and more money was spent on welfare but keeping people out of the work process.
"What we need to do is make sure we tackle poverty but tackle it in the process of trying to move them on (to work)."
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