COP26 climate negotiators late Friday entered an all-night session of talks in Glasgow, with the meeting's UK presidency targeting a global deal later than planned on Saturday.
British Prime Minister Boris Johnson appealed to richer countries to stump up more money to secure a breakthrough, exposing a central fault line at the marathon talks.
Developing economies led by India have balked at demands to do more to curb emissions without promised financial support to transition away from fossil fuels, and to adapt to the accelerating impacts of climate change.
The deadlock pushed the two-week COP26 past its scheduled end at 1800 GMT on Friday.
"I envisage formal plenary meetings in the afternoon to adopt decisions and close the session on Saturday," COP26 president Alok Sharma said in a message to delegates late Friday.
Delegates from nearly 200 nations are tasked with keeping alive the 2015 Paris goal of limiting temperature rises to 1.5 degrees Celsius, as warming-driven disasters hit home around the world.
Earlier, Johnson told reporters near London: "We do need to see the cash on the table to help the developing world to make the necessary changes."
New wording to a draft COP26 agreement on Friday called for countries to accelerate "the phase-out of unabated coal power and of inefficient subsidies for fossil fuels".
That was softer than a first version of the text, but observers said the first-ever explicit inclusion of the fuels driving the climate crisis was an important step.
"Unabated" coal plants are those that do not deploy carbon capture technology to offset some of their pollution.
The text requests countries to come back next year with updated climate pledges.
US climate envoy John Kerry said in Glasgow that fossil fuel subsidies -- including America's own -- were "insanity".
"We believe that this is existential," he told delegates.
"For many of you it is not existential in the future, it is existential today. People are dying today. All around the world the impacts are being felt, today."
The draft text also fleshes out a call for developed countries to "at least double" their funding for adaptation -- helping at-risk nations face climate impacts -- by 2025.
But tension remains over the failure of wealthy nations to meet their decade-old promise to provide $100 billion annually to help vulnerable nations prepare for the worst.
Kenyan environment minister Keriako Tobiko told delegates that failure to honour the funding pledge had severely hurt confidence.
"For myself, for Kenya, our trust has been shattered," he said, as more than 100 indigenous and other protesters marched through the summit venue demanding the rich world uphold its promises.
- 'Stark reality' -
The two-week summit began with a bang as world leaders descended on Glasgow armed with a string of headline announcements, from a commitment to slash methane emissions to a plan to save rainforests.
And negotiations received a shot in the arm on Wednesday when the United States and China -- the two largest emitters -- unveiled a joint climate action plan, although it was light on detail.
But current national emissions cutting plans, all told, would lead to 2.7C of heating, according to the UN, far in excess of the Paris target.
In a speech to delegates, European Commission Vice President Frans Timmermans held up his mobile phone with a picture of his one-year-old grandson on screen.
"If we fail -- and I mean fail now in the next few years -- he will fight with other human beings for water and food. That's the stark reality we face," he said.
He said the goal of limiting global warming to 1.5C is "about avoiding a future for our children and grandchildren that is unlivable".
- Loss and damage -
Developed nations favour a greater push on emissions reductions, something countries yet to fully electrify their grids -- and largely blameless for emissions -- feel is unfair.
Countries already battered by climate disasters such as record-breaking drought and flooding are demanding they be compensated separately for "loss and damage".
Timmermans said the EU had heard these calls "loud and clear".
"It's time to move and find the solutions that will help vulnerable countries respond to the damage and destruction the climate crisis has already caused," he said, adding: "We can find a way out of this".
But observers said that rich nations were blocking progress with an unwillingness to unlock new funding.
"If we want to get out of Glasgow with a decent outcome, we need to see real movement, particularly from the US and EU on a loss and damage facility and generally on climate finance," said Mohamed Adow, head of the Power Shift Africa think tank.