Ed Miliband today attacked David Cameron over the coalition's plans to slash child benefit in his first Prime Minister's Questions.
The new Labour leader claimed hundreds of thousands of families would lose out under the measures, aimed at helping cut the benefit bill.
Mr Miliband condemned the policy to axe the handouts for higher rate taxpayers as a 'shambles' and urged the Prime Minister to reconsider.
He claimed a family of three will lose £2,500 through the cut backs and suggested this was equal to a 6p rise in income tax.
The plan has caused outrage after it emerged stay-at-home mothers with partners earning just above the threshold will lose out but families with two working parents who are each on a salary just below the threshold will still receive the benefit.
Mr Cameron retorted that it was not fair to ask people who earned 'one sixth' of Mr Miliband's salary to pay tax to cover his child benefit.
But the Labour leader again shot back: 'It's nought out of two on straight answers' and denied he was 'defending the rich'.
'I am defending the deputy head teacher at a primary school, I am defending the police inspector, all of whom are asking a straightforward question,' he said.
And to cheers from his own benches, he quoted Mr Cameron's words at a Cameron Direct meeting during the election campaign.
A confident Mr Miliband demanded to know exactly how many families with one parent out of work would be affected by the cut.
Mr Cameron, with his deputy Nick Clegg nodding behind him, said higher-rate tax hit 15 per cent of taxpayers and admitted the decision had been 'difficult'.
But he insisted: 'As we deal with the deficit, we do have to ask better-off people to bear their fair share of the burden.'
He asked Mr Miliband to justify giving money to the more well-off, but the Opposition leader shot back: 'I may be new to this game but I think I ask the questions and he answers them.'
Mr Miliband criticised the PM for refusing to give a straight answer and insisted hundreds of thousands of families would be penalised.
'The question they are asking is this - why should a family on £45,000 when one parent stays at home lose their child benefit but a family on £80,000 where both partners are working keep theirs?
'It doesn't strike people as fair, it doesn't strike me as fair, does it strike the Prime Minister as fair?'
He said then: 'I am not going to flannel you, I am going to give it to you straight. I like child benefit. I wouldn't change child benefit.
'I wouldn't means test it, I don't think that's a good idea. I agree with the Prime Minister, why doesn't he?'
Mr Cameron insisted Labour had to face up to reality and their legacy to the coalition of the biggest budget deficit in the G20.
He accused Mr Miliband or having no alternative proposals and took his chance to quote back the new leader's words earlier this year.
He quoted former Labour Cabinet minister Alan Milburn who said 'in times of plenty, giving child benefit to high earners is a luxury we cannot afford'.
But Mr Miliband declared he should face up to the huge loss he was handing to families - with those with three children losing £2,500-a-year.
'If he wants to take people with him on deficit reduction, he has got to show that his changes are fair and reasonable,' he said.
The Prime Minister quoted Mr Miliband's own words back in July that: 'Whoever is the Labour leader will by the time of the spending review have to show they have an alternative plan.'
'Where is the alternative plan?', he demanded.
But Mr Miliband was unbowed, claiming he had shown how the Government had no defence for the policy.
'He cannot explain to families up and down the country why they are going to sustain this loss. This policy has been a shambles from day one.
'The rest of the cabinet knew nothing about it... I bet the PM wishes the BBC blackout had gone ahead.'
He added: 'Isn't it time the Prime Minister had the grown up sense to admit this - he's got it wrong, he's made the wrong decision. He should tell middle income families up and down Britain he will think again.'
Mr Cameron accused Mr Miliband of deciding to stand up for the 'squeezed middle' after years of taxing them while Labour was in government.
'It's a completely transparent political strategy to cover up the inconvenient truth that he was put where he is by the trade union movement,' he said.
Likening Mr Miliband to his predecessor, he added: 'It is just short-term tactics and political positioning. It's not red, it's Brown.'
It had been suggested Mr Cameron would be happier to face the younger Miliband brother than David, the former Foreign Secretary.
But today the 40-year-old former Energy Secretary showed he will be no easy ride as the Government battles to push through drastic spending cuts.
At the start of the session, the two leaders had both agreed they would be able to work together in the national interest on many issues.
Mr Cameron congratulated his new sparring partner but added: 'As well as wishing him well, I hope he does the job [of Opposition leader] for many, many years to come.'