Rishi Sunak is scrambling to find a compromise on permitting onshore wind amid a growing backbench Conservative rebellion, though No 10 remains fearful of a backlash from MPs who oppose windfarms. The U-turn on backing onshore wind projects would directly contradict a pledge by Sunak during his leadership campaign but Downing Street has sought to frame it as government policy. The government all but confirmed on Monday that restrictions on onshore wind would be changed in the face of the rebellion, but the row has left Sunak squeezed between two wings of the party – with a growing number of MPs also using the levelling up bill to try to put the brakes on development. Labour is also tabling a new beefed-up amendment on onshore wind, highlighting the limitations of the Conservative rebel amendment, which has been drafted by the former cabinet minister Simon Clarke and backed by Boris Johnson and Liz Truss. The Guardian understands that the former chief whip Wendy Morton has signed the amendment, bringing the total number of potential rebels to 34 – which would evaporate Sunak’s majority. The full Labour amendment, tabled on Monday night and seen by the Guardian, would remove the onerous planning restrictions that effectively ban new onshore wind in England but also require local authorities to proactively identify opportunities for renewables, including onshore wind generation. Labour will back Clarke’s amendment – putting Sunak at risk of Commons defeat – but said it was not enough to ensure real growth of onshore wind. Matthew Pennycook, the shadow housing minister, said: “Rishi Sunak is now being dragged into an inevitable U-turn by his backbenchers and, while it’s better than nothing, the Clarke amendment still leaves Britain hobbled in the race for renewables. “Because, while ending the ban, it imposes a uniquely restrictive planning regime for onshore wind that risks blocking sensible schemes, keeping bills high, and missing out on the next generation of high-skilled jobs. Under this government, we’re forced to move only at the pace of the slowest Tory backbencher.” Clarke is understood to have told Conservative backbenchers that his amendment was also a “community consent” safeguard against a future Labour government, which would be likely to make it easier for local authorities to build windfarms. “His argument is, either we do it or Labour do it in future, without this lock,” one supportive MP said. On Monday, the business and energy secretary, Grant Shapps, said there would be more onshore wind projects “where communities are in favour of it”, which would mean the end of a de facto block on such projects since 2014 under planning rules. Shapps told Sky News: “We already have quite a lot of onshore wind. There will be more, over time, particularly where communities are in favour of it. That is, I think, the key test of onshore wind: is it of benefit to communities locally? That has always been the principle for us, for quite some time now.” Pushed again on whether this was an enforced change of stance, Shapps said: “No, it’s exactly what we’ve said all along. Rishi Sunak said the other week that where onshore happens, it needs to have local agreement.” Shapps said incorrectly that Sunak had “always” argued that onshore wind could happen with local consent, adding: “To present it as some sort of massive gulf is completely untrue.” No 10 pulled a planned vote on the bill this week in the face of the rebellion on housing targets – which is separately putting the government under pressure. The added problem of Clarke’s amendment means the bill is likely to be further delayed. Labour’s amendment, which the Conservative rebels are unlikely to back, has been drafted with the Green Alliance and the Town and Country Planning Association, who have also put forward suggestions to Clarke about gaps in his amendment. Chris Venables, the head of politics at Green Alliance, said of Clarke’s amendment: “It’s not perfect as it is a campaigning amendment. The second part needs to put in place measures that ensure the planning system does genuinely shift it forward.” A new poll on Monday from the thinktank Compassion in Politics found 72% of Conservative voters supported the building of more windfarms. Overall when asked which source of energy they would prefer to see boosted in the UK, three-quarters said they would support onshore wind.