Leading figures from opposite ends of the political spectrum are calling on her to scrap the controversial cuts which have stripped the heating support from around 10 million pensioners.
Former Labour leader Jeremy Corbyn pushed his former colleague to abandon means-testing and make it once again a universal benefit. This comes as fears mount that many of the very poorest retirees will not get the allowance because they have not applied for pension credit.
Campaigners warn that pensioners are enduring sleepless nights because they are so worried about how they will pay for the heating.
Mr Corbyn asked what other services will now be subject to means-testing, saying: “Universal payments ensure everyone who needs it, gets it, and reduces the stigma attached to those who rely on it the most. What next for means testing? The NHS?”
He said the Labour Government had “opted to take money away from people who were promised things would change”. The independent MP said people would “not be fooled by ministers’ attempts to feign regret over cruel decisions they know they don’t have to take”.
Former Conservative Work and Pensions Secretary Mel Stride has written to Ms Reeves warning that even if people do apply for pension credit it may not arrive in time for the “crucial period when the weather is coldest”.
Mr Stride told Ms Reeves this was a debacle of her own making, saying: “The fact is that none of this was necessary. This was a political choice that your government took.
“You yourself have admitted that cutting the winter fuel payment may not actually save the Treasury any money and your own party members voted in favour of a motion calling you to reverse your decision.”
Pressing for an urgent u-turn, he added: “I and many pensioners are worried that further punishing measures could be coming in the Budget. I call on you to make the choice – and it is a choice – to reverse the damage that has been done so far and ensure that pensioners are adequately protected and spared much misery.”
Former Conservative leader Sir Iain Duncan Smith said the decision to radically cut the fuel payments was an “unmitigated disaster”.
He said: “It won’t raise that much money but will damage the lives of those pensioners who are often struggling to make ends meet and who don’t have the option, often, of being able to increase their income because they are long past the age of retirement. This is a betrayal of pensioners.”
Labour MP Rachael Maskell said the Government had a “responsibility” to help the elderly and the vulnerable who are now in “fuel poverty”.
She said: “The winter fuel payments were a lifeline to so many and yet since the announced cut to those not in receipt of pension credit, just 84,600 out of the 880,000 eligible people, to the end of September, have applied for pension credit, leaving too many out in the cold this winter.”
Caroline Abrahams of Age UK said that although the state pension will increase next year this will do “nothing to help pensioners this winter”.
Pressing the Chancellor to take action, she said: “Rather than trying to defend the indefensible so far as the impact of its decision on poor pensioners is concerned, the Government should accept the reality and take decisive action to protect them this winter. We know some older people are having sleepless nights because of their anxiety about how they will afford their heating bills.
“The Budget is the Government’s opportunity to put their minds at rest and we strongly urge them to take it.”
A Government spokesman said: “Anyone who makes a successful claim for pension credit and meets the winter fuel payment eligibility criteria will receive their payment, and we are deploying 450 additional staff to process the expected increase in claims.
“Over a million pensioners will still receive the winter fuel payment, and our drive to boost pension credit take up has already seen a 152 per cent increase in claims. Many others will also benefit from the £150 warm home discount to help with energy bills over winter while our extension of the household support fund will help with the cost of food, heating and bills.”