Environmental campaigners walked out en-masse from climate talks here in Warsaw saying they felt no progress was possible.
Several hundred people left the national stadium venue amid anger over the slow pace of negotiations.
But UK climate secretary Ed Davey told reporters he still expected "modest progress" to be made.
And other negotiators indicated that a deal was possible on some of the most contentious issues.
The talks began almost two weeks ago in the wake of Typhoon Haiyan with an emotional plea for rapid movement from the Philippines lead delegate.
Yeb Sano, said it was time to "stop this madness" but his call has fallen on deaf ears according to many civil society groups like Oxfam, WWF and Action Aid.
"Governments are not doing enough," said Oxfam's Celine Charveriat, speaking to BBC News as she walked out of the talks.
"We need to tell them you are not allowed to make a mockery of this process. We can't continue to watch in silence. Enough is enough."
The conference has shipped a number of blows in recent days. Japan surprised the meeting by announcing that it would have to significantly revise its targets on emissions cuts.
Instead of being able to cut their carbon dioxide by 25% below 1990 levels, the Japanese admitted they would actually rise by 3%.
There was also annoyance among negotiators from developing countries about the attitude of Australia, which, under new prime minister Tony Abbott, has signalled a more sceptical approach to climate issues.
Delegates were upset to see two members of the Australian team wearing T-shirts in a late night negotiation session, during which they were said to be blocking progress on key texts.
But campaigners have reserved most of their wrath for Poland. The government gave its backing to a meeting of the coal industry in the capital on Monday. On Wednesday, the environment minister who was chairing these talks was sacked in a government re-shuffle.
Executive director of Greenpeace International, Kumi Naidoo, was sharply critical of the overall handling of the talks.
"The Polish government has done its best to turn these talks into a showcase for the coal industry," he said.
But some of those engaged in trying to move the process forward were not so downbeat.
UK climate secretary Ed Davey said he was hopeful of "modest progress" and didn't expect the walkout by green campaigners to have an impact.
"The UK government works very well with NGOS, but I don't think their walkout affects the talks."
Mr Davey struck a hopeful note on two of the major issues outstanding at these negotiations.
Participants are trying to develop a framework for a global deal in 2015, that would be legally binding and applicable to all.
However the text that has been circulating here is said to lacking in clarity and in ambition. Mr Davey believes it will emerge from these talks in a better shape.
"I can see a good landing ground on that, but we've got a bit of work to do and I think we may well be up for a long time tonight."
He was also hopeful that a deal could be done on the most contentious aspect, loss and damage. This is something that developing nations are desperately keen to see some progress on.
Richer countries are fighting tooth and nail against the idea of a legally binding compensation arrangement, that in their words, would see them on the hook for every storm in every part of the world, forever.
However, ambassador Ronny Jumeau, from the Alliance of Small Island States (Aosis), also struck a cautiously optimistic note. He said there were different definitions of compensation that could allow some movement in the talks.
"It depends how you view compensation," he told BBC News.
"It doesn't necessarily mean I am blaming someone for it."
"We are past the blame game here, there is no black and white division between whose emissions caused what where."
The talks are due to finish late on Friday but the expectation is that, as usual, it will be sometime on Saturday before the final gavel falls.