Support grew on Thursday for an EU plan to agree a global climate change pact with binding targets by 2015, after poor nations vulnerable to climate change forged alliances with developed countries.
The European Union said it was encouraged its road map to legally binding commitments by 2015 to cut greenhouse gas emissions was gaining traction at the talks, which are due to wrap up in the South African port of Durban on Friday.
U.S. climate change envoy Todd Stern said Washington supported an EU roadmap to a new treaty, and Canadian Environment Minister Peter Kent said Ottawa had forged a partnership with small island states which could be swamped by the rising sea levels caused by global warming.
We're not setting a hard target on this date...(but) 2015 would be a reasonable target to set to pull together any new climate change regime, Peter Kent told reporters.
If we can reach one before 2015, that would be good, if it takes somewhat longer, that would be fine...but we can't leave Durban without a firm agreement, he said.
Days earlier Kent had said that the Kyoto Protocol, the only legally binding accord on reducing carbon emissions, was in the past.
With the EU pact gaining momentum, pressure could shift to the developing world's biggest polluters -- China and India -- to come on board.
A group of 48 of the least developed countries said it now backed the European plan for a firm timetable, joining African nations and 43 small island states.
The EU roadmap is totally in play right now. The shift of the least developed countries and AOSIS (Alliance of Small Island States) to work with the EU potentially shows some kind of roadmap coming out of here, said Jennifer Morgan at the World Resources Institute.
Reflecting the changing mood in Durban, Brazil, an emerging economy that is a key player in climate negotiations, also said there was convergence on a deal in Durban.
It think it's possible, Brazil's chief negotiator Luiz Alberto Figueiredo told reporters, when asked if Durban could agree a date by which a legally binding accord could be reached.
We are in favour of negotiating a legally binding instrument that will cover the phase after 2020. The parties are moving there, it's a question of completing the negotiations, he said.
All countries will be inside and they will be bound by this new instrument, he added.
Nevertheless, some delegates warned the talks could still break down on the final day on Friday as the dates and precise legal form of a treaty still have to be thrashed out.
One EU source said U.S. negotiators still opposed specific targets because they had no mandate to sign up to a legally binding deal. Environmental legislation is the subject of intense wrangling in the U.S. Congress, which must ratify any treaty.
They can agree to a road map leading nowhere but not a road map leading to a legally binding deal, which is what the EU wants, said the EU source, speaking on condition of anonymity, said of U.S. negotiators.
Previously, the United States has said it supported discussions that would lead to an emission cut deal, even one that was legally binding, but would not commit to set dates or a set outcome.
It is completely off base to suggest the U.S. is proposing it will delay action to 2020, U.S. climate envoy Stern told reporters. The EU has called for a roadmap (to a future deal). We support that.
Poor states most threatened by the rising sea levels caused by global warming were sceptical.
Let me see that in the negotiation room, let me see that in the text, said Grenada's Foreign Minister Karl Hood, representing small island nations.
Speaking before Canada's announcement, Britain's climate envoy Chris Huhne said the European Union was not prepared to accept a deal in Durban at any price, saying there had to be real meat on the bones of any agreement.
We're not interested in just papering over the cracks. We're interested in something that really does provide us with a roadmap to a single overarching global agreement which delivers a solution to climate change, he told reporters.
If we don't have a credible agreement, we will not agree here, we will go away from Durban and there won't be an agreement here and we'll wait to a point where we can get a credible agreement.
(Additional reporting by Jon Herskovitz, Andrew Allan and Agnieszka Flak and Michael Szabo; Editing by Jon Boyle)