Negotiators at the UN-sponsored climate summit in Paris have come up with a draft agreement that will be presented to ministers at 10:30 GMT, according to a French government source.
The accord aims to transform the world's fossil fuel-driven economy within decades and rein in global warming.
"There is a draft agreement," the source told Reuters news agency on Thursday. "It is being translated. For it to become a deal, it would have to be adopted."
After four years of negotiations under the auspices of the UN, Laurent Fabius, French foreign minister, is expected to unveil the text of the climate deal on Thursday.
Officials from 195 nations were locked in negotiations through the night, seeking to resolve the final sticking points: the phrasing of a goal for phasing out carbon emissions later this century, as well as the frequency of further negotiations meant to encourage even faster action.
"All the conditions are in place to have a universal, ambitious final deal," Fabius announced late on Friday, urging a drive to resolve what are still deep disagreements on issues such as finance for developing nations.
"There has never been such a strong momentum."
Powerful symbol
The result, including pledges to expend billions of dollars in funding to ease the shift to low-carbon fuels and to help developing nations cope with impacts of climate change ranging from floods to heat waves, is likely to be praised by many for its ambition, and criticised by others for its lack thereof.
If successful, it will be a powerful symbol to world citizens and a signal to investors that for the first time in over 20 years the world will have a common vision for cutting back on the greenhouse gas emissions blamed for overheating the planet, and a plan for ending two centuries of fossil fuel dominance.
By charting a common course, they hope executives and investors will be more willing to spend trillions of dollars to replace coal-fired power with solar panels and windmills.
"It will be up to business, consumers, citizens and particularly investors to finish the job," Reuters news agency quoted Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research, as saying.
Yet unlike the Kyoto Protocol, the last major climate deal agreed in 1997, the Paris pact will not be a legally binding treaty, something that would almost certainly fail to pass the US Congress, for instance.
Instead, it will be largely up to each nation to pursue greener growth in its own way, making good on detailed pledges submitted ahead of the two-week summit.
