Plans to hit diesel drivers with a "toxin tax" are likely to be shelved until after the election amid concerns that it could cost the Conservatives votes.
Ministers have been drawing up plans for a crackdown on air pollution in seven cities which could see diesel cars hit by daily charges of even banned during peak hours.
The plans have proved hugely controversial and motoring organisations have warned that drivers are being "punished" for following Government policy and buying diesel cars.
The Government has been drawing up plans for a diesel scrappage scheme, under which drivers of older more polluting vehicles would be offered a £2,000 incentive to trade in their vehicles.
However The Telegraph understands that the crackdown is now likely to be delayed until after the General Election because the Government has already gone into "purdah", after which officials have to be neutral.
A Defra spokesman said: “We are firmly committed to improving the UK’s air quality and cutting harmful emissions. We are seeking an extension to comply with pre-election propriety rules.”
It is one of a series of controversial policies which are being shelved because of the election. Ministers have also abandoned a huge rise in probate charges which had infuriated and MPs and risked becoming a major campaign issue.
The move, which would have taken fees from just £155 to as much to £20,000 depending on the size of the estate, was announced in the budget last month.
It has now been scrapped because there is too little parliamentary time before the election to push it through.
The crackdown on diesel drivers comes after Defra was taken to the High Court by environmental campaigners ClientEarth over its last air quality plan, published in 2015.
The Government had until Monday to publish its plans, but The Daily Telegraph understands that ministers are pushing for that to be extended until after the election.
Other policies that are likely to be delayed until after the election include a new national funding formula for schools. The policy has provoked a backlash from Tory MPs amid concerns that their constituencies will lose out on funding. The Government will also delay a review into high stakes "fixed odds betting terminals".