Keir Starmer is set to water down electric car targets in a blow to Ed Miliband's Net Zero push.

The PM is said to have overruled his Cabinet minister by moving to loosen rules on what proportion of new sales must be EVs by 2030.

The level is now expected to be reduced from 80 per cent to 50 per cent, following pressure from industry and unions. 

Sir Keir's intervention is the latest sign of tensions with Mr Miliband, who fuelled the PM's defence funding meltdown by resisting cuts to his budgets.

The premier's allies suspect that the former leader is angling to be Chancellor in an Andy Burnham government. He is believed to have told Sir Keir privately that he should lay out a departure timetable. 

The Zero Emission Vehicle (ZEV) mandate requires manufacturers to increase the share of electric-only car sales to 33 per cent by the end of this year, or face penalties.

The mandate was set to continue to increase annually before reaching 80 per cent in 2030.

At that point, sales of new petrol and diesel cars are due to be banned, with only hybrid vehicles allowed to make up the remaining 20 per cent. It is not clear exactly what the rules would be if the mandate is cut to 50 per cent. 

Motor firms had warned the restrictions could lead them to pull investment from the UK. There have been complaints about having to offer huge incentives to lure people into buying more expensive EVs. 

Unite general secretary Sharon Graham welcomed the apparent shift, as reported by the Sunday Times.

'This is a huge victory. UK car workers have been increasingly fearful for their jobs,' she said.

'Government at the highest level has listened to the concerns of Unite and is now set to act decisively to protect the jobs of UK automotive workers.

'As Unite had said the failure to act would have been an act of self-harm to a sector which is a jewel in the crown of UK manufacturing.'

The change will be subject to a consultation and could require backing from devolved administrations – raising the prospect of a clash between Westminster, Holyrood and the Senedd. 

Rishi Sunak tried to delay the ban on sales of new petrol and diesel from 2030 to 2035 when the Tories were in power.

But Labour reinstated the earlier deadline, with hybrid vehicles due to be phased out in 2035.

Mr Miliband previously insisted it was 'very important' that the Government 'strengthened our commitment to our world-leading EV transition plan'.

Sir Keir's desperate efforts to drum up more defence funding have been hampered by Mr Miliband. 

The PM was hit with the resignation of John Healey as Defence Secretary on Thursday, after he rejected proposals for a £10billion boost to funding over the next four year. Forces chiefs had warned the Defence Investment Plan needed to fill a £28billion gap.

The Treasury has been trying to get other departments to agree to cuts in order to free up money. 

But Mr Miliband has been resisting demands for savings of at least 1 per cent within the Department for Energy Security and Net Zero.

That could amount to more than £600million from the capital budget over the five-year spending period – potentially affecting support for heat pumps and carbon capture.