Sir Keir Starmer admitted his new government will be “unpopular” amid a backlash over axing winter fuel payments for most pensioners.

The Prime Minister sought to defend the controversial decision to restrict the allowance to only those on pension credit ahead of a crunch vote on Tuesday.

In his first major interview since entering No 10, he told the BBC’s Sunday with Laura Kuenssberg programme: “We’re going to have to be unpopular.

“Tough decisions are tough decisions. Popular decisions aren’t tough, they are easy.

“When we talk about tough decisions, I’m talking about tough decisions, the things the last government ran away from, that governments traditionally run away from.

“I’m convinced that because they’ve run away from difficult decisions, we haven’t got the change we need for the country.”

Sir Keir refused to say if Labour MPs will be stripped of the whip if they vote against cuts to winter fuel payments in the House of Commons.

He said: “That will be a matter for the chief whip. We’re going into a vote. I’m glad we’re having a vote, because I think it’s very important for Parliament to speak on this.

“But every Labour MP was elected in on the same mandate as I was, which was to deliver the change that we need for the country over the time we’ve got in office.

“I’m absolutely convinced that we will only deliver that change, I’m absolutely determined we will, if we do the difficult things.

“Now, I know they’re unpopular, I know they’re difficult. Of course they’re tough choices.”

The Prime Minister also repeated his claim of a £22billion black hole in the public finances left by the previous Tory government being to blame for the winter fuel payment cuts, which they have denied.

He said: “I am absolutely clear in my own mind that we can’t bring about that change if we don’t fix the fundamentals and stabilise our economy.

“Equally clear in my mind, in order to deliver the change which we will deliver, we have to fix the foundations now. And that’s tough decisions.”

Sir Keir added: “Talking to many pensioners in the last two or three years, the things that have hit the most and hardest are inflation, because it got out of control under the last Government, energy bills, because the steps that were needed to be taken years ago weren’t taken, and the cost of living.

“I’m determined that no pensioner will ever be put through that before. That’s why we’re fixing the foundations now, tough though that may be.”

Shadow health secretary Wes Streeting said he was not “remotely happy” about cutting the winter fuel allowance.

Campaigners have expressed fears that the policy could put more older people who cannot afford to heat their homes in hospital.

Mr Streeting told Sky News: “I think it is a tough choice, and we’ve had plenty of political criticism for it, I think, which demonstrates the political pain of it.

“I’m not remotely happy about it, and I’m not remotely happy about having to say to some of my constituents, I’m sorry that I’m going into work this week to vote for something that will take money away from you.”

The Cabinet minister also warned of more “tough choices” in the autumn budget where Chancellor Rachel Reeves is widely expected to hike taxes.

He said: “And by the way, it’s not just pensioners. We’ve got a budget and the spending review coming up, there are, there are difficult choices coming, and we’re going to have to look carefully at how we make sure we can build the future for our country.”

Conservative Party chairman Richard Fuller urged MPs to “do the right thing” and oppose the stripping of winter fuel payments for around 10 million older people on Tuesday.

He said: “This week’s vote on the Conservative’s motion is a vote to protect millions of vulnerable pensioners.

“No MP from any party should run scared from stopping Labour’s cruel plans to cut the winter fuel payments.

“It’s time for all Members of Parliament to put aside party politics and do the right thing.”

The PM faces a potential Labour rebellion when MPs vote on scrapping winter fuel payments.

Rosie Duffield, the Labour MP for Canterbury, is among the party’s backbenchers who have said they will not vote with the Government.

Ms Reeves in July unveiled plans to limit winter fuel payments, which were previously available to all pensioners.

The change means that only those who claim pension credit and other means-tested benefits will receive the additional fuel payments.

It is expected to reduce the number of pensioners in receipt of the up to £300 payment by 10million, from 11.4million to 1.5million – saving around £1.4billion this year.