Rishi Sunak has suffered one of the biggest rebellions of his premiership as dozens of Tory MPs including Suella Braverman and Dame Priti Patel voted against his net zero plans.
The two former home secretaries joined backbenchers to oppose a quota on sales of electric cars.
The measure was passed with Labour’s support on Monday evening but will be a worry to Mr Sunak as Tory rebels reached the “magic number” of 26 – the number of his own MPs that would overturn his majority.
It came minutes after he suffered his first defeat in the Commons, with MPs – including 22 Conservatives – voting to speed up compensation for victims of the infected blood scandal.
Senior Tories are worried that Mr Sunak, who announced in September that a ban on sales of petrol and diesel cars would be pushed back by five years, is reneging on the commitment.
The controversial mandate compels car manufacturers to ensure that at least 22 per cent of their vehicles sold will be electric from Jan 1.
By 2030, 80 per cent of cars sold will need to be zero emission, even though the outright ban on petrol and diesel does not come in until 2035.
David Jones, a former Cabinet minister who voted against the measure, said it “completely negates” Mr Sunak’s pledge to delay net zero targets.
He told The Telegraph: “[The vote] took everybody by surprise. We all assumed that there was going to be a more sensible and gradual transition to net zero, and this has completely undone that.
“I think the whips need to listen a lot more carefully to their flock … Two rebellions in one evening is something that should be avoided.”
The rebellion was larger than the opposition to Mr Sunak’s Windsor Framework, which 22 Tories voted against.
Greg Smith, a member of the Conservative net zero scrutiny group, said he felt let down by the mandate and that rebels were sticking to the Prime Minister’s position from September. He warned the Government: “Don’t try something like this again, because we have the numbers”.
The policy was also opposed by Sir Iain Duncan Smith, the former Conservative leader, Sir Jacob Rees-Mogg, the former business secretary, and Sir John Redwood, the former Welsh secretary.
A letter to the Prime Minister earlier this month from 40 Conservative MPs and peers warned of a rebellion against the “anti-motorist” legislation.
The letter, signed by Dame Priti and others, read: “Many in the car industry do not regard this as a realistic aim, but the attempt to get there through legal coercion is likely to cause enormous harm.
“If the cost of buying and running an EV will become cheaper than petrol and diesel cars, mandating them with this law is unnecessary. This law is anti-consumer, anti-choice and anti-motorist, and will only leave the public poorer. Car ownership could once again be restricted to the privileged few.”
A government spokesman said: “We’re on the side of drivers, which is why we have set out a fairer, more proportionate route to net zero and pushed back the date to end new petrol and diesel car sales to 2035 – aligning the UK with other countries like France, Germany and Italy.
“We are also backing British jobs, with the Zero Emission Vehicle mandate giving the car industry the certainty they need to keep investing in the UK and employing skilled workers across the country.
“We are helping people to make the switch to zero emission vehicles with £2 billion of investment in grants and chargepoint support, making these vehicles more accessible to drivers across the country.”