Efforts to craft a global accord to combat climate change stumbled on Friday with China and many other nations refusing to yield ground, forcing host France to extend the U.N. summit by a day to overcome stubborn divisions.

After a night of often fraught discussions on issues including a proposed goal to phase out net greenhouse gas emissions in the second half of the century, French Foreign Minister Laurent Fabius conceded the two-week summit would not end on Friday as planned.

He said a final text, meant to chart a way to far wider use of greener energy such as wind and solar power, would now be presented to nearly 200 nations for review only on Saturday, a day later than planned.

Delegates said China was resisting calls, led by the United States and the European Union, for all nations to review and update their national plans for curbing greenhouse gas emissions every five years.

President Xi Jinping has already promised that carbon dioxide emissions from China’s rapidly developing economy will start falling from around 2030, and does not want to revisit the target. Delegates said China had also reasserted demands that developed nations do far more to curb greenhouse gas emissions, mostly the result of burning coal, gas and oil.

Gao Feng, the Chinese Foreign Ministry’s special representative on climate change, played down differences between China and the United States, saying: “There are no special differences... A deal is getting closer.”

“In fact, we have been pushing all kinds of countries, whether it is the EU or others. We wish they can all be more ambitious,” he said.

Red lines

Many other countries were also holding their ground.

Saudi Arabia said it would resist a new 27-page draft text calling for a rise in global temperatures to be limited to “well below” 2 degrees Celsius (3.6 Fahrenheit) above pre-industrial levels – a plan that it fears could jeopardise oil production.

The draft text, released on Thursday night, also sets a target of “greenhouse gas emissions neutrality in the second half of the century” – more ambitious than previous drafts in shifting to cleaner energy sources.

“Major countries have entrenched behind their red lines instead of advancing on compromise,” said Matthieu Orphelin, spokesman for the Nicolas Hulot Foundation. Hulot is French President Francois Hollande’s envoy on climate change.

Delegates said the talks were also split on who should pay for developing nations to move to low-carbon economies and to mitigate the effects of global warming, which scientists say will raise sea levels and accelerate desertification as well as triggering more intense and frequent storms, floods and droughts.

One source said the “night was very hard”.

But Fabius, speaking on French BFMTV, maintained an optimistic tone. “The atmosphere is good, things are positive, things are going in the right direction,” he said.

U.N. climate talks almost always run into overtime at the weekend and one senior European official praised Fabius.

“Everybody’s to blame – there are no good guys or bad guys. It’s going well. The French are allowing everyone to have their say,” he said.

Xi spoke with U.S. President Barack Obama by telephone, Chinese state television reported.

It was unclear what they had discussed, or whether the call signalled new divisions between the world’s largest emitters, who struck a landmark climate accord last year.

Xi said the two nations “must strengthen coordination with all parties and work together to ensure the Paris climate summit reaches an accord as scheduled”, according to state television.