Green industrialist Dale Vince will join campaigners calling on Labour to introduce stronger environmental protections.
Mr Vince is among those urging the new Government to back the Climate and Nature Bill, a proposed law which would require the UK to meet its environmental targets.
The Bill, which has been introduced in successive parliaments without progressing into law, has previously garnered widespread support across the Labour movement.
At a Labour Party fringe event on Sunday night, Ecotricity founder and Labour donor Mr Vince will call on Sir Keir Starmer to support the “essential” Bill, alongside former Tory minister Chris Skidmore.
Energy minister Alex Sobel, who while in opposition was the Bill’s most recent champion in the previous Parliament, is also expected to attend.
Speaking ahead of the fringe event, Mr Vince said: “If we’re serious about tackling the biggest threat we face, climate breakdown and nature’s destruction, we need the right laws to guide us, and we need them fast.
“Let’s be real, we’ve got a small window left and the next five years are make or break. That’s where the Climate and Nature Bill comes in.
“It’s the only thing out there that tackles the twin crises of climate and biodiversity at the same time.”
Mr Skidmore, who was the energy minister who signed net zero into law, said the new Government “should be demonstrating how to raise climate and nature ambition – now – as we approach the 10th anniversary of the Paris accords”.
He described the Bill as the “Climate Change Act 2 for the new generation to carry forward”.
“It’s the legislation Britain needs,” he added.