Sir Keir Starmer faces his first major rebellion this week amid warnings cuts to winter fuel payments will become his "poll tax moment".

Angry MPs branded the decision "brutal" and "shameful" and fear the government will be blamed if pensioners die in the cold.

The Prime Minister is fighting to keep the lid on an explosive row as backbenchers and union leaders pile on pressure for a U-turn.

Twelve Labour rebels have signed a Commons motion demanding a re-think, backed by six colleagues suspended for voting against the child benefit cap.

Last night government whips were accused of making "terrifying" threats to keep their troops in line ahead of a crunch vote on Tuesday. On the same day, Labour's union paymasters will back the rebels in a vote at the TUC conference in Brighton.

Sir Keir is under fire after ruling that up to 10 million elderly people will lose the winter fuel payment - which pays up to £300 - to plug a "black hole" in public finances.

The decision was announced just before train drivers were given inflation-busting pay rises. While ministers are confident of winning Tuesday's vote, they are concerned about the long-term effects of simmering discontent on the back benches.

Some fear the winter fuel row will dog him like the poll tax, the disastrous policy that brought down former Tory PM Margaret Thatcher.

But as one insider observed: "Thatcher had been in power for 11 years when she made that blunder. Keir has been in office for just 65 days."

Party insiders said new MPs were "terrified" by the "ruthless" strong-arming of party whips.

Few Labour MPs, if any will, vote against the cuts but whips fear many will abstain or to back the Government only under duress, with insiders fearing the leadership is storing up discontent that will encourage future battles.

Union activists also want a U-turn, with Unite, Usdaw and the PCS opposing the cuts.

Former home secretary James Cleverly, who is standing for the Tory leadership, said last night: "As the reality of what he is doing dawns on his MPs, Starmer is facing his very own poll tax moment."

Labour's Rosie Duffield, a former whip, warned: "We are actually going to see people die."

She said: "All MPs have been inundated with emails. It's not just from those constituents affected, it's also their families and people who are really concerned about the most vulnerable of those constituents.

"People who have ongoing health concerns, learning disabilities, the absolutely most vulnerable of the older people are the people we have got to look out for."

Ms Duffield highlighted research showing 4,950 died last winter due to cold, saying: "It just feels particularly brutal."

She added: "We know that pensioners living on just £13,000 a year will lose out. I find it particularly shameful that the lowest-paid MP, backbenchers like me, get £91,000 a year and here we are making decisions that will affect people on £13,000."

But highlighting the ruthless operation to ensure MPs fall into line, she said: "The government has made it very clear to MPs how they are going to behave towards us if we do vote against."

Shadow Work and Pensions Secretary Mel Stride, a Tory leadership hopeful, will lead opposition to the cuts in the Commons this week, and appeal to Labour MPs to follow their consciences.

He said: "If in your heart you know that this is deeply unfair and going to be punished for a lot of people who are vulnerable and not able to change their circumstances, we're giving you the chance now to vote this down."

Former Work and Pensions Secretary Esther McVey said the move could destroy Sir Keir's reputation in a similar way to the disastrous "mini-budget" which forced former Prime Minister Liz Truss out of Number 10, or economic chaos which forced the UK to leave the ERM under John Major.

Ten million pensioners will no longer receive winter fuel payments of up to £300 under the means-testing plan announced by Chancellor Rachel Reeves. Only people on Pension Credit, including individuals with incomes below £11,344 or pensioner couples with a joint income below £17,313, will continue to be eligible.

Backbenchers are pleading with Ms Reeves to announce help for low-income pensioners before Tuesday's vote but Downing Street sources indicated there will be no concessions.

Number 10 pointed out that the Government was already helping people in need after announcing last week that it is providing almost £500 million to help people struggling with bills.

There is anger over the decision to hold a vote at all, as this is not required in order to introduce means-testing. The Government has in fact already introduced the required regulations and they come into force on September 16.

But a cross-party House of Lords Committee condemned Ministers for rushing in the changes, saying: "The policy seems to be being introduced at a pace that does not permit appropriate scrutiny."

The House of Lords Secondary Legislation Scrutiny Committee said it was "concerning" that winter fuel payments are being cut after energy regulator Ofgem had announced that the cost of gas and electricity for a typical household will rise by £149 per year, an increase of 10 percent.

Labour MPs also fear the cuts will cause a winter NHS crisis, with hospitals overwhelmed by pensioners who have fallen ill because they cannot afford to heat their homes.

Former shadow cabinet minister Rachael Maskell, who worked in the NHS for 20 years, said: "If people go cold the pressure in the health service over winter will be astronomical. It will make seeing a GP or getting into A&E much harder."

The motion signed by a dozen Labour MPs was also backed by ex-Labour MPs currently suspended, including former Shadow Chancellor John McDonnell, and two independent MPs elected on a pro-Gaza platform.

A Government spokesman said: "We are absolutely committed to supporting pensioners and giving them the dignity and security they deserve in retirement. That's why through our commitment to protect the triple lock, over 12 million pensioners could see their State Pensions increase by almost a thousand pounds over the next five years.

"But given the dire state of the public finances we have inherited, it's right that we target support to those who need it most while we take the difficult decisions needed to fix the foundations of our economy. Over a million pensioners will continue to receive the Winter Fuel Payment and eligible pensioners will also be able to benefit from the £150 Warm Home Discount scheme from October to help with their energy bills over winter.

"We are urging pensioners to come forward and check their eligibility for Pension Credit to ensure as many people in need as possible have access to this support."

The End Fuel Poverty Coalition has estimated that 4,950 excess winter deaths in the UK were caused by living in cold homes over winter and in a report last year Prof Sir Chris Whitty, the Chief Medical Officer for England, said "cold homes and fuel poverty are directly linked to excess winter deaths".