Liberal Democrat leader Sir Ed Davey has called for a Commons vote on the decision to withdraw the winter fuel payment from millions of pensioners, describing it as the government’s “first big mistake”.

Around 10 million pensioners not receiving benefits will lose the payment of up to £300 from mid-September, saving £1.4bn this financial year.

Chancellor Rachel Reeves has blamed the move on a £22bn “black hole” in the public finances she says she has inherited from the Conservatives. They have rejected that and are also pushing for a vote.

Labour MPs loyal to the prime minister have told the BBC of their growing unease over the decision to axe the fuel payments.

One senior Labour backbencher, who is a strong supporter of Sir Keir Starmer, told BBC Newsnight the move was a “mean means test”.

“There are people who do not qualify for pension credit who are struggling – they will really feel the loss of the winter fuel payments.”

Other normally loyal Labour MPs have told Newsnight they understand the chancellor needs to take tough action after discovering the state of the public finances. But they are deeply uneasy about singling out pensioners.

One said: “It looks like she (the chancellor) has picked out pensioners. It really is not good politics.”

Another Labour MP said: “We are getting a lot of correspondence on this. And it’s not centrally generated by campaigning organisations. It is individual people telling their stories. That will unsettle colleagues.”

Sir Ed Davey told BBC Breakfast: “I think pensioners will be going to this winter really worried if Parliament doesn’t stop the government from doing this.”

Since Labour took office, the Lib Dems – who now have a record 72 seats – have been broadly supportive of the new government. But Sir Ed signalled this had its limits in his BBC interview.

He acknowledged that the government had a “budget problem”, a legacy from the Conservatives, he said, “which is really, really tough”.

But he added: “I don’t think the way to balance the books is to take away this crucial support for millions of pensioners, just as we’re going into winter when fuel bills are going up.”

Sir Ed said there were “other choices” available to balance the books, and his party would support getting the “very wealthiest in our country to pay more” to fund investment in public services.

Asked whether he accepted that some pensioners did not need the winter fuel payment, he said: “I think we’ve got to focus on the millions of people who do need this.”

He said he hoped a Commons vote can be held within two weeks of Parliament’s return on Monday on the winter fuel issue.

The Conservatives, who have already submitted their own motion calling for a Commons debate and vote, also oppose the scrapping of universal winter fuel payments to pensioners.

They have called for cheap, non-renewable energy to be prioritised over “reckless net zero targets” to help struggling families this winter.

But it is not clear that either the Lib Dems or the Conservatives, the largest opposition party, will be able to force a vote.

Labour has a huge Commons majority and so far only one Labour MP, Rachael Maskell, has put their head over the parapet by publicly demanding a climbdown on the winter fuel allowance.

Former shadow chancellor John McDonnell, who was elected as a Labour MP on 4 July, has joined calls for a rethink.

But he and six other MPs have been suspended from the parliamentary party for six months for rebelling against the government by calling for a lifting of the two-child benefit cap.

Both the prime minister and the chancellor have defended scrapping universal winter fuel payments as necessary, accusing the Tories of mishandling the public finances.

On Tuesday, Sir Keir warned that the Budget at the end of October would ask people to “accept short-term pain for long-term good”.

Charity Age UK says it “strongly” opposes means-testing the payment because it means “as many as two million pensioners who badly need the money to stay warm this winter will not receive it and will be in serious trouble as a result”.