The clock is ticking down on the annual UN climate meeting, this year hosted in the Brazilian Amazon city of Belem -- where a fight over phasing out oil, coal and gas is a core outstanding issue.

"The Europeans will be isolated, that much is clear," the source said. Some fear being held responsible for the summit's failure, the source added, speaking on the sidelines of an emergency closed-door meeting.

The Brazilian draft contains no reference on a "roadmap" for phasing out fossil fuels, despite calls from President Luiz Inacio Lula da Silva and more than 80 European, Latin American, and island nations to include such language.

The EU has submitted its own revised proposal, reaffirming the commitment made two years ago at COP28 in Dubai to transition away from oil, gas and coal.

"We're not asking for any new language. And even when it comes to already agreed language, we're being told 'no,'" the source said with frustration.

"The real question is whether Europe is prepared to stand alone and say, 'We're sorry, but...this is as far as we can go,'" they said.

Finance is another central fault line, with developing nations demanding more support to cope with climate impacts such as floods and droughts, and to transition to cleaner energy.

"We've heard all the oil-producing countries, Russia, etc., tell us they're ready to accept this text as a compromise," said the European representative.

"They're trying to make us out to be the villains of the operation, claiming that we're actually just being difficult because we're unhappy with the finances, which is just a lie," the source added. "We're at an impasse."