Rishi Sunak is planning to row back on some of the government’s net zero policies that impose a direct cost on consumers as the Conservatives attempt to create a dividing line with Labour before the next election. The Guardian understands that the move, expected to be announced in a major speech this Friday, could include delaying a ban on the sale of new petrol and diesel cars and watering down the phasing out of gas boilers. The prime minister is also expected to drop plans for new energy-efficiency targets for private rented homes after ministers considered imposing fines on landlords who failed to upgrade their properties. Sunak said on Tuesday that the government remained committed to the net zero target but planned to hit it in a “better, more proportionate” way. He said that politicians of “all the stripes” have not been honest about “costs and trade offs”. In an apparent dig at Boris Johnson, he accused previous governments of taking “the easy way out, saying we can have it all”. Sunak recommitted to the target of net zero emissions by 2050, insisting his government was not “losing our ambition or abandoning our commitments” on climate change. However, he appeared to defend his decision to row back on other targets by claiming he was putting “the long-term interests of our country before the short-term political needs of the moment”, despite some Tory MPs accusing him of doing the opposite. The prime minister said: “This realism doesn’t mean losing our ambition or abandoning our commitments. Far from it. I am proud that Britain is leading the world on climate change. We are committed to net zero by 2050 and the agreements we have made internationally – but doing so in a better, more proportionate way.” The move was immediately condemned by senior Tories, who argued that it would be the “greatest mistake of his premiership” and that watering down the targets could cost jobs, put up energy bills and damage the UK’s international reputation. Business groups also expressed dismay, with Emma Pinchbeck, chief executive of Energy UK, saying that it was “not a great look for UK plc” and was at odds with what the sector had been told by ministers. “I just came out of a meeting where a chunk of the British economy was assured by ministers that net zero was a top priority and that policy stability was crucial for investors. Now this,” she said. One Downing Street insider suggested late on Tuesday that there had been “sheer bloody panic” inside No 10 at how badly the policy was received. Many of the targets, such as banning the sale of new petrol and diesel cars by 2030 to promote electric vehicles – which it is believed will be pushed back five years – have been cited by industry as crucial for growth in this sector in the UK. The BBC reported that Sunak was also planning to delay the ban on off-grid oil boilers from 2026 to 2035, with only an 80% phase-out target at that date. The phasing out of gas boilers, also expected by 2035, could be watered down too, with only 80% removed by then. It was also suggested that the prime minister would announce there would be no new taxes to discourage flying and no new policies to change people’s diets or encourage carpooling. He is also expected to rule out proposed recycling schemes with multiple bins.The prime minister has been under pressure from the Conservative right to delay or even abandon costly green policies after the party’s victory in the Uxbridge byelection – in part a protest vote at the expansion of London’s low-emissions scheme. However, environmental groups could challenge any decision to water down green policies in court as the government has a legal obligation to set out in detail how it will meet its net zero target by 2050, with clear carbon budgets for different sectors. Tory MP Chris Skidmore, a former energy minister who led a recent review into net zero by the government, condemned the move: “If this is true, the decision will cost the UK jobs, inward investment and future economic growth that could have been ours by committing to the industries of the future. “Ultimately, the people who will pay the price for this will be householders, whose bills will remain higher as a result of inefficient fossil fuels and being dependent on volatile international fossil fuel prices. Rishi Sunak still has time to think again and not make the greatest mistake of his premiership.” Simon Clarke, a former levelling up secretary, said his Middlesbrough constituents overwhelmingly supported net zero policies. “We should be exceptionally careful of seeking to extract political advantage on this issue when the efforts of successive prime ministers – the majority of them Conservative – have been dedicated to upholding what Margaret Thatcher called a ‘full repairing lease’ on our planet,” he said. The Tory peer Zac Goldsmith, who accused Sunak of being “uninterested” in the climate when he quit as environment minister in June, described the move as a “moment of shame” for the UK. “Around the world, one of the few areas where the UK really is looked up to is on climate and the environment. Today Sunak is dismantling that credibility, not by accident but by choice,” he said. “His short stint as PM will be remembered as the moment the UK turned its back on the world and on future generations. A moment of shame.” Alok Sharma, the Conservative MP who chaired the Cop26 summit also criticised the idea, saying the UK “ has been a leader on climate action but we cannot rest on our laurels”. He tweeted: “For any party to resile from this agenda will not help economically or electorally.” Sam Hall, who runs the Conservative Environment Network of more than 150 backbench MPs and peers, warned that the move could be electorally as well as economically damaging. “It will be important to see the final details of this, but slowing down climate action would damage the Conservatives electorally on an issue voters care deeply about and undermine the UK’s green economy, following a string of recent electric vehicle investment decisions this summer,” he said. Caroline Lucas, the sole Green MP, tweeted a tennis image, saying: “Game, set & match to the climate dinosaurs?” She added: “Sunak is economically illiterate, historically inaccurate and environmentally bone-headed. This absurd rollback will mean higher energy bills, colder homes, fewer jobs, more air pollution & more climate chaos.” The shadow climate secretary, Ed Miliband, said: “This is a complete farce from a Tory government that literally does not know what they are doing day to day. Thirteen years of failed energy policy has led to an energy bills crisis, weakened our energy security, lost jobs and failed on the climate crisis.”