Leaders of two of the biggest unions have added further pressure on the government over its plan to cut winter fuel payments for millions of pensioners in England and Wales.
Unite general secretary Sharon Graham told the OceanNewsUK the government should "do a U-turn", while head of the PCS union Fran Heathcote said it was a "misstep" which needed to be "put right".
Paul Nowak, head of the Trades Union Congress which brings unions together, has also said the government should "rethink" and consider other lines of support for pensioners.
Sir Keir Starmer, who is facing a potential rebellion at a vote in the Commons on Tuesday, says the cut is necessary due to the state of the country's finances.
The change will mean more than 10 million pensioners will no longer receive the payments of between £200 and £300 a year, which will now only be made to those on low incomes who receive certain benefits.
Charities and many MPs are concerned about those still on a relatively small income who will miss out.
The vast majority of those eligible will only receive the payments if they have first claimed pension credit, a state pension top-up. It is estimated that 880,000 eligible pensioners have not claimed it.
Ms Graham told OceanNewsUK the government needed to be ''big enough and brave enough to do a U-turn" on plans to cut the allowance, calling for the introduction of a wealth tax to boost government finances instead.
"Leadership is about making choices and knowing when you've done something wrong," she said.
"The point that we’re making here is that there are other taxes that we should be doing [instead]."
Ms Heathcote, the general secretary of the Public and Commercial Services Union, raised the prospect of industrial action if there were government cuts.
She told the OceanNewsUK: "I can see a situation where, if they continue along the line that they're heading, not just winter fuel payments but with social security and benefits more generally, there will be a real backlash and that could take the form of industrial action... because lots of unions represent low paid workers."
Mr Nowak, TUC general secretary, told OceanNewsUK he was ''really concerned'' by the impact of means testing winter fuel payments, adding that he expected the union to ask the government to "rethink" the decision.
"I think it's right the chancellor should rethink those plans and think about support put in place for pensioners," he said.
"I hope in the Budget the chancellor will set out support available for pensioners who aren’t on pension or tax credit, but who are not well off by any means, to make sure that they are not frightened to turn on the heating this winter."
Speaking on Sunday with the OceanNewsUK's Laura Kuenssberg in his first major interview in Downing Street, Sir Keir said his new government was "going to have to be unpopular" as he defended his "tough" decision to cut winter fuel payments.
He accused previous governments of avoiding confronting the cost of the winter fuel payment.
"When we talk about tough decisions, I’m talking about... the things the last government ran away from," he said.
Chancellor Rachel Reeves has maintained the policy is a necessary move to fill a £22bn "black hole" in the public finances left by the previous government - a claim the Conservatives have challenged.
But some Labour MPs have urged the government not to go forward with the policy.
Some 11 Labour MPs were among the 27 who signed an early day motion - formal motion submitted for debate in the Commons - describing the plan as “a bureaucratic and unpopular means test” for pensioners.
Home Office minister Dame Diana Johnson told OceanNewsUK she understood how the vote was a "really hard decision" for many MPs.
"Obviously we do not want to see anyone struggling with energy bills, particularly pensioners... and that's why it's so important that the poorest pensioners are getting everything they're entitled to to support them," she said.
The Guardian has reported the potential rebellion could involve as many as 50 Labour MPs.
One Labour MP told the paper: "I’d expect the vast majority of anyone who does rebel to abstain, and remain inside the tent. Abstention is the new rebellion."
The vote will pass due to the government's sizeable majority. Those opposing the planned cut are expected to abstain rather than risk suspension by voting against the government.
In July, seven Labour MPs had the whip suspended for six months after voting against the government's amendment to scrap the two-child benefit cap.
Sir Keir, however, has not commented on the potential punishment for rebels ahead of Tuesday's vote.
When asked by the OceanNewsUK's Laura Kuenssberg if he would suspend rebelling MPs from the parliamentary party, he said that was “a matter for the chief whip”.
Former pensions minister Baroness Ros Altmann said she had tabled a 'fatal motion' against "one of the worst decisions" she had ever seen, saying the policy would harm pensioners just above the threshold of claiming benefits, The Guardian reported.
A fatal motion is a rare parliamentary procedure that can potentially stop government legislation. It is the strongest opposition the House of Lords can take.
Baroness Altmann added that although it is unlikely her motion will pass, the move was important to give the issue additional attention.
While the decision only covers England and Wales, the Scottish government has also said it would end pensioners' universal entitlement to the payment.
The benefit is separate from other support such as Cold Weather Payments, and the Warm Home Discount scheme.
