A new attempt is being made to win over MPs to incapacity benefit reforms, with the government arguing that the current system "perpetuates hardship".
Labour MPs have rebelled on previous plans to reform the benefit
Work and Pensions Secretary John Hutton has released new figures which he says show a link between high numbers of claimants and deprivation.
He has written to 100 MPs - almost all Labour - in areas with the highest number of incapacity benefit claimants.
A Green Paper on plans for changes to the benefit is due later this month.
Mr Hutton is trying to win over Labour MPs concerned about the changes. Sixty-five Labour MPs rebelled against planned reforms to the benefit in 1999.
The government is hoping reforms to be announced later this month will take at least one million people off incapacity benefit.
The benefit, for sick and disabled people, is paid to around 1.8m people.
The Conservatives agree the system needs reform but say they think Tony Blair may have to water down his proposals to head off a rebellion among his own MPs.
Suggestions that the benefit could be means tested or a limit placed on the amount of time people can spend on it are now thought to have been discarded.
Mr Hutton told BBC Radio 4's Today programme he would publish his proposals to reform the current "failing system" at the end of this month.
He promised to handle the issue "sensitively and carefully" but said the reforms would still be "radical".
"I did not come into politics to make poor people poorer," he said.
The changes would be based on giving extra support for people on Incapacity Benefit to get jobs.
In return, they would have a responsibility to take part in those programmes and return to work.
Mr Hutton says he will be sensitive over the reforms
Mr Hutton played down the prospect of major backbench rebellions, saying there was a "groundswell of opinion" behind changing the current system.
In his letter to MPs Mr Hutton told them a third of their constituents lived in the worst pockets of deprivation in the country, more than five times as many as in the rest of the country.
He said the "striking" link in the research showed the case for radical reform.
"I do not believe we should accept a system that perpetuates hardship and denies people the opportunity to better their lives by accessing the world of work," he said.
'No virility tests'
Mr Hutton's own constituency of Barrow and Furness in Cumbria is among the 100 highlighted.
The prime minister's official spokesman urged people to address the core issue rather than starting "virility tests" of how radical the government's plans were.
"That core issue is of people in deprived areas being on incapacity benefit an trapped in a vicious circle where they find it difficult to get off incapacity benefit," said the spokesman.
He also pointed out that 90% of claimants want to get back into work.
Labour MP Ian Davidson welcomed what he said was a change in the "mood music" over the government's plans in recent months.
"We want to make sure that this is not a means of saving money for the Treasury, nor a means of punishing those who are in difficulties," he said.
Mr Davidson said he hoped the government would accept amendments to its plans to prevent any "unintended consequences", otherwise some MPs could vote against parts of the plans.
Conservative shadow minister Philip Hammond said his party would back sensible proposals which genuinely helped people who were able to work back into sustainable jobs.
But he said the government should have started earlier to try to persuade Labour MPs of the need for reform earlier.
Liberal Democrat spokesman David Laws said incapacity benefit must be made more flexible, with more staff on hand to help people back into work.