Countries at the COP29 climate summit were warned on Wednesday that the “hardest part” was about to start in talks over how much money should be provided to developing countries to help them cope with climate change.

Figuring out what form that funding takes, who pays and how much is the main task of this year’s annual UN climate talks. With a notional Friday deadline looming, frustration over the lack of progress was starting to seep out of the negotiating rooms.

Yalchin Rafiyev, the chief negotiator of the summit’s host Azerbaijan said, “Now the hardest part begins,” ahead of a fresh text which is due to be released at midnight in the capital Baku.

Progress at the annual summit is typically marked through regular draft documents that get whittled down to a final deal.

Wealthy and developing countries are sharply divided over the size of the new goal. It will replace a 2020 pledge by developed countries — delivered two years late — to provide $100 billion per year in climate finance.

Uganda’s Adonia Ayebare, who chairs the G77 and China group of more than 130 developing countries, said its demand was for wealthy nations to provide $1.3 trillion in public climate finance per year.

“The frustration is that the other side has not given us a counteroffer,” Ayebare told Reuters. “We are hearing $300bn. But if that is true, that’s really not acceptable. It’s embarrassing,” he said.

Another developing country negotiator told Reuters that the European Union had floated $200bn or $300bn in informal talks. But on Wednesday, the EU maintained it did not have an official position on the number.

EU climate commissioner Wopke Hoekstra said the bloc was not willing to talk about the figure until it had more structural details, adding: “Otherwise you will have a shopping basket with a price, but you don’t know exactly what is in there.”

Countries are still at odds over whether large, still-developing economies, including the world’s second-biggest economy China, will contribute towards the goal.

Egypt’s Minister of Environment Yasmine Fouad said countries had agreed better off developing nations would not be legally obliged to pay in.

Azerbaijan’s Rafiyev said the COP29 presidency would produce a tighter text overnight. In simple terms, a 25-page document stuffed with multiple options for almost every paragraph needs to become a two-page document that can be refined in the final days and then adopted.

“We will have shorter, more concise, straight to the point, texts,” Rafiyev said.

Opec secretary general says oil gift from God

While talks on finance have been slow, those on speeding up efforts to cut climate-damaging emissions are proving as tough.

After agreeing on a landmark deal to transition away from fossil fuels in Dubai last year, countries had so far failed to agree on language that would take that work forward in Baku.

Austria’s climate minister Leonore Gewessler told Reuters that the Arab group of countries led by Saudi Arabia had been “very vocal in watering down the mitigation part” of negotiations.

A representative for Saudi Arabia’s delegation did not immediately respond to a request for comment.

Saudi Energy Minister Prince Abdulaziz bin Salman has previously described the Dubai deal as a menu of options — suggesting not all countries will select quitting fossil fuels as their chosen path forward.

Opec Secretary General Haitham Al Ghais used a speech at the summit to say crude oil and natural gas were a gift from God, echoing the words of Azerbaijan President Ilham Aliyev, whose opening speech hit out at Western critics of the industry.

Getting a fresh commitment to cutting emissions more quickly has been thrown into sharp relief by a growing belief among scientists that the world’s aspirational goal of limiting global warming to 1.5°C could soon be beyond reach.

Recent trends, if not changed, “will drive us to cross 1.5°C in the early 2030s or even slightly before”, said French climatologist Robert Vautard.

Vautrad is co-chair of the UN Intergovernmental Panel on Climate Change’s Working Group 1 which assesses the physical science of climate change.