MPs are being urged to back a target to slash carbon emissions from the power sector by 2030 in a vote this week.
Businesses, environmental organisations, faith groups and trade unions are all calling on MPs to back an amendment to the Energy Bill, due to be debated tomorrow, which would significantly cut average emissions from power generation.
The amendment was propose by Conservative MP and Chairman of the Energy and Climate Change Select Committee Tim Yeo and committee member and Labour MP Barry Gardiner,
If passed it would force the Government to set a target by April 1 next year and supporters say it would send an important signal to investors to put money into low-carbon energy infrastructure and supply chains.
The Government has been accused of sending out mixed signals, with Chancellor George Osborne expressing support for a new "dash for gas" instead of a drive toward renewables and other low-carbon technology in the 2020s.
The Government's own climate advisers, the Committee on Climate Change, have backed the target to cut emissions by 2030 and said that investing in low-carbon power such as wind farms and nuclear reactors in the 2020s could save consumers billions of pounds compared to relying on gas.
In a statement a coalition of 55 groups called on MPs to back the amendment which would "commit the UK to have a near carbon-free power sector by 2030", and to push forward with the Energy Bill which aims to stimulate £110bn in investment to cut emissions from electricity generation and keep the lights on.
They said: "We represent different parts of society but are united in the belief that the Energy Bill represents a major opportunity to put the UK firmly on track to becoming a world leading low-carbon economy, to boost employment and to show genuine leadership in the fight against dangerous climate change."
The Government has said it was legislating to bring in a decarbonisation target in 2016, but ministers have been warned that a delay to the target will see the UK lose out to other countries on green jobs and investment.
Greenpeace executive director John Sauven says that the amendment was very important because without it the Energy Bill became "a bit aimless".
"This is the point the investors and business people are making: you've got to be really clear about what your route map is and where you want to get to," he says.
He says investors were concerned that George Osborne wanted to halt the drive towards green growth and jobs after 2020 and back a new dash for gas, and the amendment would get rid of the sense of uncertainty around energy policy.
He adds: "One of the problems David Cameron faces is there's a rump of the Tory party that George Osborne plays to, but it's not really representative of the opinion out there.
"I think that the amendment has so much backing outside Parliament, which is almost unprecedented if you look at the range of support for this, it would be very hard for the Government to ignore everything going on out there."
Friends of the Earth suggested that around 300 MPs had already indicated their support for the decarbonisation target.
Labour is backing the amendment, while a 2030 target to slash emissions is Lib Dem policy.
Andy Atkins, executive director at Friends of the Earth's says: "This is the last chance saloon for the Liberal Democrats to swing the vote and block Osborne's dash for gas. MPs of all parties must back a target to make Britain a world leader in clean power.
"The Energy Bill is simply not fit for purpose unless it does what investors say is needed and commit the UK to clean British energy; thousands of jobs as well as our climate are at stake."
But business group CBI says investment decisions would be made on the detail of the Energy Bill, such as the long term guaranteed price that will be paid for the generation of low carbon electricity under the reforms, not the target. The CBI says there must be no more delays to the Energy Bill.
Chief policy director, Katja Hall, says: "Debates about the effect of including a target in the Bill should not be allowed to prevent critical policy details being tied down. Vital investment decisions are hanging in the balance."
Ahead of the vote Energy and Climate Change Secretary Ed Davey said: "The Energy Bill will lead to a massive decarbonisation of the power sector by 2030, and will enable the UK to cut its economy-wide emissions by 50 per cent by 2030.
"We are also legislating to set a decarbonisation target range for the power sector in 2016, something no political party had in their manifesto, but an issue that this Coalition Government has addressed head on.
"I urge Honourable Members to support this Bill, which is a world-first and will make the UK a destination of choice for investors in low-carbon energy, stimulating £110bn private sector investment into the economy, which will drive growth and jobs."