Official figures for child poverty are being published today as Labour issued a warning to ministers not to try to change the way it is measured.
Campaigners have voiced concern that the Government is seeking to "move the goalposts" as planned welfare cuts push more families into relative poverty.
Reports have suggested Prime Minister David Cameron could even move to repeal the Child Poverty Act - passed by the last Labour government - which commits the Government to ensuring fewer than one in 10 children are living in relative poverty by 2020.
With ministers having reaffirmed their intention to slash a further £12 billion off the welfare bill, the publication of the latest Households Below Average Income data comes at a highly sensitive time politically.
A report earlier this year by the Institute for Fiscal Studies suggested they could see the first increase in child poverty in 10 years, with the numbers living in relative poverty rising to 2.5 million in 2013-14 - a 300,000 increase on the previous year.
Expectations that the Government could now seek changes were raised after Mr Cameron used a speech on Monday to complain about the "absurd" way the current system operates.
He said using relative poverty as a measure meant that even a small increase to the state pension produced a rise in average incomes which in turn resulted in more children falling into relative poverty.
Downing Street confirmed that the issue was discussed by ministers at Cabinet on Tuesday, but the Prime Minister's spokeswoman played down suggestions that change was imminent.
"There was a discussion about the Government's approach to child poverty and how the Government wants to tackle the root causes not treat the symptoms of poverty," she said.
"As part of this, we would be looking at how we focus our efforts on things that will drive real change in terms of child poverty and eliminating child poverty.
"We want an approach where measures are helping to drive change."
Nevertheless, Mr Cameron's concerns have been echoed by the Centre for Social Justice (CSJ) - the think tank established by Work and Pensions Secretary Iain Duncan Smith.
"Despite some outstanding recent progress on job creation and social justice measures, the official child poverty targets don't help Government to change the lives of the poorest children," said CSJ director Christian Guy.
"Under the current measures, a family can be moved into or out of poverty without any change in their circumstances. A child can go to bed in poverty and wake up out of it, despite nothing meaningful having changed in their lives."
For Labour, shadow chancellor Chris Leslie said all the signs were that the Conservatives were intent on ditching a previous cross-party commitment to reducing child poverty.
"David Cameron used to say he wanted 'to be judged on how we tackle poverty'. Yet his instincts are apparently to cut child tax credits for the majority of working families and to dump the statistics that might embarrass him," he said.
"Instead of shifting the goalposts, the Prime Minister should take responsibility and tackle low pay, not attack the low-paid.
"The Child Poverty Act places one of the most important duties on a government - to ensure that children in the 21st century do not grow up suffering deprivation or lacking the necessities that most of us take for granted."