Keir Starmer has said painful decisions such as cutting winter fuel payment to save £1.4bn a year are necessary as failure to act would be simply “putting a lick of paint over the damp”.

The prime minister described the process of taking decisions “that aren’t going to be popular” as part of a strategy of “strip down the joint, rebuild the house”.

Speaking to reporters on the plane to Washington DC in the US, Starmer said the remedial action he was prepared to do was “painful” and “difficult”.

But he added: “The alternative is to put a lick of paint over the damp and pretend job done, which might get a round of applause now but will not get a round of applause in six months, 12 months and years down the line, when everybody then appreciates you haven’t actually changed anything.”

Starmer gave his defence as he was pressed on how he felt about his popularity falling in opinion polls.

The cut to winter fuel allowance removes the previously universal annual payment of £200 or £300, depending on age, from all but the poorest pensioners – those who receive income-linked benefits such as pension credit.

Ministers have launched a campaign to encourage all eligible pensioners to claim pension credit, and thus also still receive the winter fuel allowance.

But a Commons vote on the policy on Tuesday, forced by the Conservatives, saw one Labour MP rebel and 52 abstain, although Downing Street said most of that group had permission to miss the vote.

The Tories have been pushing for the publication of an impact assessment, but No 10 said earlier this week one had not been carried out.

However, the Conservatives have highlighted previous Labour research from 2017 which claimed Conservative plans to scrap the winter fuel payment for better-off pensioners could lead to almost 4,000 additional deaths over winter.

Research released by Ipsos said 46% of people polled viewed Starmer unfavourably and 32% favourably – his joint worst as Labour leader.

The only other time so many people were saying they were unhappy with his performance was just after Labour lost the Hartlepool byelection in 2021.

Labour is still much more popular with voters than the Conservative party. But, over the summer, the number of people saying they view Labour, and key figures like Keir Starmer and Rachel Reeves, unfavourably has risen significantly, with 45% of people saying they view Labour unfavourably and 36% saying they viewed it favourably.

Asked about the polls, and whether people were expecting too much, Starmer said: “I’ll be judged when we get to the next election, on whether I delivered against the promises that I made.

“The promises I made were to stabilise and grow the economy so that everybody feels better off across the country; to ensure we’ve got a health service which isn’t just back on its feet, but is actually fit for the future; to ensure that we’ve got renewable energy, which will ensure that we’ve got cheaper energy, independence over our energy supply; and take the next generation of jobs.

“That we’ve got skills and education so every single young person can go as far as their talent will lead them, and that everybody feels safe and secure in their own community.”

Keiran Pedley, director of politics at Ipsos, said: “There are some early warning signs in these numbers for Keir Starmer and Labour. While the next general election is several years away – and perceptions of Labour remain stronger than perceptions of the Conservative party – these figures do represent a sharp drop from those recorded in August.”