Labour is planning to make the climate a key focus for its election campaign, putting its net zero commitments “up in lights”, and drawing a clear link between the “chaos” of the Conservative government and the effects of the climate crisis. Fears over the climate – exemplified by a sopping Rishi Sunak calling the general election in a downpour on the same day scientists warned about the increased likelihood of seemingly “never-ending” autumn and winter rain – will be tied strongly to what Labour will portray as a polluting and careless Tory vein of climate denial. “We are up for this fight,” one Labour insider said. “This is going to be huge.” Sunak appears to have invited such a response, using his speech to attack “environmental dogma” he implied was to blame for high energy prices, a remark green campaigners condemned as “divisive” and “dangerous rhetoric”, as well as a potential vote loser. Tom Burke, a veteran government adviser and co-founder of the E3G thinktank, said: “The reference to environmental dogma in Sunak’s speech was a big mistake. If Labour win this election, it will be very clear that the Tories have misread public opinion on the climate and lost the culture war they are trying to wage.” It is a stark contrast to the picture a mere 100 days ago, when Labour appeared to be in turmoil over its environmental commitments. For months, speculation had increased about whether Keir Starmer would renege on his longstanding commitment to invest £28bn a year on a low-carbon transformation of the UK economy or not. In February, after tortuous internal negotiations, the £28bn plan was watered down to about £15bn a year. The Labour leader said the change was necessary because of high inflation and the worsening economic outlook, and the state of public finances under the Conservatives. The Guardian understands that some voices within the top echelons of Labour had urged caution, worried that the spending commitment would be a focus of attack. It still is, even after the change of tack. After the Uxbridge byelection last summer, when the London mayor, Sadiq Khan’s plan to widen the capital’s ultra-low emissions zone (Ulez) was seen by some as a factor in Labour’s narrow failure to win the seat, senior figures also worried that net zero policies could be soft targets for the Conservatives and a turnoff for some voters. Khan’s decisive re-election victory, after a campaign unabashedly championing the Ulez, put paid to many of those fears earlier this month. Questions over Labour’s commitment to net zero have been firmly settled, insiders say. The leadership sees the environment as a core issue for voters and a strong dividing line between Labour and the Tories. Labour has long sought to show that pursuing net zero is a source of economic growth and will bring down the cost of living, especially for poorer families, through cheaper renewable energy and home insulation. The message appears to be getting through. A party spokesperson said: “The choice at this election is clear: a Conservative government that pollutes our rivers with record levels of toxic sewage, is led by and funded by climate deniers and fails to meet our climate and nature targets; or a Labour government that will restore nature, deliver the largest investment in clean energy in our history so we can cut bills for families, make Britain energy independent and tackle the climate crisis to protect our home for our children and grandchildren. “Britain needs change. It’s time to stop the chaos, turn the page and start to rebuild.” Nurturing a low-carbon economy must be a priority for the next government, green campaigners insisted. Mel Evans, a climate team leader at Greenpeace, said: “Investing in green technologies of the future would give the UK the bold green industrial strategy it needs that will create millions of jobs, grow our flailing economy, make us more energy independent, ease pressure on the NHS, and help the cost of living and climate crises all at the same time.” “This is the opportunity Labour should seize in their election manifesto,” she added. Starmer has pledged to create a new publicly owned energy company to invest in renewables, capitalised with £8.3bn, as well as a national wealth fund for investment in electric vehicle manufacturing, green steel, carbon capture and storage and other green technologies, with a British jobs bonus aimed at attracting more private investment in green companies in the UK’s industrial heartlands. A warm homes plan is intended to double current spending on home insulation. On Wednesday, the National Grid unveiled plans to double investment in the UK electricity network to £31bn over the next five years. The energy secretary, Claire Coutinho, hailed this as “a huge vote of confidence” in Tory plans. But the investment could also assist Labour, as upgrading the grid is a necessary step to decarbonising the power sector. Sunak’s comments on the steps of No 10 on Wednesday made clear that Labour will face an onslaught from the Conservatives on the climate and net zero. But Labour will also have to convince voters on the other side, people who think the party is not environmentally minded enough, and might be tempted by the Greens or Liberal Democrats instead. “Labour’s rhetoric on the climate emergency is strong but they have to back it up with firm plans and commitments,” said Mike Childs, the head of science, policy and research at Friends of the Earth. “After scrapping their £28bn investment there are serious questions about how they will insulate our heat-leaking homes, boost our depleted bus network, and ensure that our homegrown wind and solar resources are developed at the speed and scale we so urgently require.” Childs said far more detailed commitments would be needed. “If Labour forms the next government, they will have to produce a comprehensive and lawful climate plan that meets our domestic carbon budgets and our international commitment to reduce emissions by two-thirds by 2030 – or face possible legal action if it falls short,” he said. “Warm words on how to tackle an overheating planet are not enough. We need urgent action now.”