Jeremy Corbyn has again called for the Chancellor to step down following Iain Duncan Smith's shock resignation last Friday.
The Labour leader said on ITV's Good Morning Britain that George Osborne's budget "simply doesn't add up."
At the very core of it is unfairness and injustice within our society. That is what the Tory Party is about. That is Iain Duncan Smith is about. That is what the Chancellor of the Exchequer is about.
His Budget unraveled within hours of him presenting it as his budgets usually do. Duncan Smith then had to resign.
I think it's time George Osborne considered his position because he has put something forward that simply does not add up.
Conservative MP Nicky Morgan has claimed the proposed cuts to disability benefits, over which some Tory backbenchers are threatening to revolt, are just a "suggestion" and nothing has yet been put in place to instigate them.
Speaking on BBC1's Question Time Morgan appeared to be attempting to row back on the £1.3 billion a year cut to Personal Independence Payments (PIPs) that was announced in this week's Budget saying it was still being "discussed".
This is a measure that is still being discussed in Government.
It is something that has been put forward, there has been a review, there has been a suggestion, we are not ready to bring the legislation forward.
We want there to be control of the welfare budget. We also made it very clear that we are not going to balance the books on the back of the poor and the disabled and we absolutely hold to that promise.
The education secretary's comments came amid growing unrest within the party over the squeeze on PIP's which could see an estimated 370,000 people possibly being £3,500 worse off a year.
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Labour leadership hopeful Andy Burnham has called the Institute for Fiscal Studies' verdict on the Budget as "devastating" and condemned Iain Duncan Smith's Commons celebrations.
The IFS said 13 million families will be worse off because of the freeze on working-age benefits.
The Work and Pensions Secretary was seen on camera cheering when the Chancellor announced the new National Living Wage yesterday - a celebration that Burnham said showed the "nasty party was well and truly back".
The Chancellor has been accused of an "outrageous" tax hike on motorists that will lead to more uninsured drivers on the country's roads.
George Osborne raised the Insurance Premium Tax in yesterday's Budget from 6% to 9.5%, a move which the AA said could backfire.
"Drivers shouldn’t be dancing in the streets or at the pumps due to a promised freeze in fuel duty," said Edmund King, AA president.
"The sting is in the tail. The Insurance Premium Tax increase on the average car insurance policy is still equivalent to a fuel duty increase of almost 2p per litre. Either way drivers are being hit in their pockets.
"This is an outrageous hike which could well backfire by leading to an increase in uninsured drivers"
The Budget is unfair to Catholics because of plans to limit to two the number of children eligible for tax credits from April 2017, a Labour MP has suggested.
Intervening on Work and Pensions Secretary Iain Duncan Smith in the Commons, his Labour shadow, Helen Goodman asked: "Could you explain to the House why cutting tax credits for large families is a fair thing to do when it will be concentrated... on families where children are living in poverty, on Roman Catholic families, on Catholics from other minorities.
"Don't you understand that every child matters?"
Mr Duncan Smith replied: "I have for some time believed the way tax credits operated distorted the system so there were far too many families not going into work, living in bigger and bigger houses, with larger families subsidised by the state when many others, the vast majority of families in Britain, make decisions about how many children they can have and the houses they can live in.
"Getting that balance back is about getting fairness back into the system."
Thirteen million families will on average lose £260 each year because of the freeze on working-age benefits, according to the Institute for Fiscal Studies.
Describing George Osborne's Budget as "regressive", IFS director Paul Johnson said it took "much more" from the poor than the rich, adding that after 2017 most benefit rates will have fallen to pre-2008 levels.
"The biggest single cut to welfare spending is set to come from extending the freeze in working age benefits, tax credits and local housing allowance out to 2020," he said.
"That will affect 13 million families who will lose an average of £260 a year."
The IFS also cast doubts on the Chancellor's claim to be delivering a "lower-tax" society, pointing out that the Treasury's own documents show tax increases totalling £6.5 billion a year by 2020.
"Given the array of benefits, it is not surprising that the changes overall are regressive, taking much more from poorer households than richer ones", Mr Johnson added.