Keir Starmer will pledge to put “good, union jobs” at the heart of Labour’s energy policy during a speech to one of its biggest donor unions after its general secretary criticised a proposed ban on oil and gas expansion. He will speak at the GMB’s annual conference on Tuesday, a day after he tried to calm a growing rift with its leadership over Labour’s energy policy. In a speech pledging to put workers at the heart of the party’s planned transition to green energy, the Labour leader will also seek to portray the prime minister as London-centric and overly concerned with banking. “If the City of London races ahead while the rest of Britain stagnates, as long as there was a hint of growth on his spreadsheet, Rishi Sunak would think that’s fine. But it’s not,” Starmer will tell the GMB congress in Brighton. “If you leave this many people behind, a nation cannot grow fairly. We can’t do it with low wages. We can’t do it with insecure jobs and bad work, with a stand-aside state that doesn’t fight for the future, without a proper industrial strategy.” Starmer – who is likely to be challenged on his opposition towards Labour MPs joining picket lines – will also pledge that Labour in government will work with unions, strengthening their role in society and urging businesses such as Amazon to recognise them. “We can create a new business model for Britain, one which creates economic security and grows not just our productivity, but our hope and our optimism. Labour in government will work with unions. We will always see the fight for working people as our driving purpose.” His appearance comes amid discontent among Labour’s union base over a pledge to block all new domestic oil and gas developments if it wins power. The party is proposing instead to invest heavily in renewable sources such as wind and also in nuclear power. Gary Smith, the general secretary of the GMB, said on Sunday that Labour had “got it wrong” and risked creating “a cliff-edge with oil and gas extraction from the North Sea”. In an apparent attempt to reassure union critics, Starmer stressed on Monday that “oil and gas will be part of our energy mix for many, many years to come”. Speaking during a visit to the Hinkley C nuclear power project in Somerset, he said: “We have a once-in-a-generation opportunity now to seize the jobs of the future. Oil and gas will be part of that because, where there are existing licences, they will go on to the 2050s.” However, only a couple of hours later Smith used a speech to the Brighton conference to reiterate his criticism, urging Labour to focus on a “mix of energy sources” if it gains power, including oil and gas. He said that – while the union wanted a Labour government – he disagreed with its energy policy. “We have to fix and secure our energy supply if we are to face down threats from authoritarian regimes in the world and find a workable way to achieve net zero,” Smith said. The Unite union has also criticised Labour’s stance. Its general secretary, Sharon Graham, said last week that the UK needed a properly planned transition that would “guarantee jobs, pay and conditions for all the tens of thousands of workers in the North Sea and supporting industries”. Starmer’s plans have received significant support from a range of high-profile groups, including other trade unions, environmental campaigners and even the Women’s Institute. Last year, Unite and the GMB each gave Labour about £1.2m. Starmer said on Monday that Labour talks to the GMB “all the time”. Energy policy is expected to be a key battleground for Labour in the run-up to the next election. The energy crisis, provoked by Russia’s invasion of Ukraine, has fuelled debate over Britain’s energy security and plans for green jobs.