By Oliver Hotham and Alex Stevenson
The coalition believes the wealthiest should "bear the heaviest burden", Nick Clegg has told MPs, ahead of the expected demise of the 50p top rate in tomorrow's Budget.
In a heated exchange with Harriet Harman during deputy prime minister's questions, Mr Clegg said the government is committed to progressive taxation and protecting the poor.
Mr Clegg was forced to respond to a quote from last November when he had said that, when asked about cutting the top rate of tax, he believed giving a tax cut to the very rich was not a priority.
Emphasing his commitment to continuing to make the rich pay more in tax, Mr Clegg said: "The priority for me, and for the whole coalition government, will be to provide real help to people of middle to low level incomes who face higher prices [and] who've had to face great difficulties because of the economic enclosure she and her colleagues presided over in government.
"Whatever changes there are to this bit of the tax system or that bit of the tax system, we on this side of the House believe the wealthy should pay more because the broadest shoulders should bear the heaviest burden."
Ms Harman said Mr Clegg's support for the chancellor was "a step too far" and cited it as further evidence that the deputy prime minister had given up on his principles.
"I suppose we shouldn't be surprised after what they've done on VAT, police, tuition fees," she said.
"By signing up to cutting the top rate of tax, he's giving thousands of pounds to the very rich, while at the same time cutting tax credits for people struggling to make ends meet. Surely, even by Lib Dem standards, that's a step too far."
The deputy prime minister insisted that the government was working to fix Labour's "economic enclosure", however.
He cited the government's policies of raising the tax threshold, increasing the state pension and improvements to the pupil premium as demonstrating their commitment to helping alleviate the effects of poverty.
Mr Clegg added: "That's a record I'm proud of."