Processed coal is ready to be transported from a processing plant in Huaibei in east China's Anhui province. China remains the world's largest greenhouse gas emitter and its output keeps rising. (AFP/GETTY IMAGES)

The nearly 200 nations participating in the U.N. Framework Convention of Climate Change negotiations remain divided on three central questions: whether industrialized nations will embrace new climate targets under the existing 1997 Kyoto Protocol; how to move forward on establishing a broader global warming pact; and how to administer international assistance to poor nations hard hit by climate impacts.

The European Union has called for a “road map” that would outline negotiations aimed at reaching a legally binding treaty by 2020 or earlier. While the Obama administration has resisted the idea of signing onto a process which will automatically lead to a legal deal, U.S. special envoy for climate change Todd Stern told reporters Thursday that when it comes to a road map, “We support that.”

“It is completely off base to suggest that the U.S. is proposing that we delay action until 2020,” he said.

But afterward, State Department spokeswoman Emily Cain issued a statement making it clear the U.S. negotiating position remained unchanged: “Todd Stern said in his press conference today that the United States could support a process to negotiate a new climate accord. He did not say that the United States supports a legally binding agreement as the result of that process.”

Alden Meyer, director of strategy and policy for the Union of Concerned Scientists, wrote in an e-mail that the U.S. was blocking progress at the talks by refusing to soften its position.

“This is clearly a case of major-league back-peddling,” Meyer wrote. “Todd is saying he can only support such a process if it’s a road map to nowhere.”

Dessima Williams, who serves as Grenada’s permanent representative to the U.N. and chair of the Alliance of Small Island States, said all the world’s major greenhouse gas emitters must agree to forge a new climate treaty before 2020 or risk disastrous climate consequences..

“We cannot start negotiating in 2015. We must end in 2015,” she said, adding that under this timetable, “we can start acting to bring down emissions well before” the end of the decade.

Officials from developing countries emphasized that delegates must also reach a consensus on how to operate the Green Fund, which will help distribute climate assistance governments of richer nations will give to poorer ones.

“If there is no Green Fund mechanism after this conference, we should be frank and call this a failure,” said Costa Rica’s environment minister, Rene Castro. “There is no mistake about this.”

Andrea Rudnick, head of the climate change office at Chile’s Ministry of Environment, said international funding is “critical” for her country and others like it to pursue policies that will cut greenhouse gas emissions.

“We need that incentive in order to shift the economic sectors and make the changes,” Rudnick said, adding that even as Latin American countries call for steep emissions cuts by industrialized nations, “we’re leading by example.”

Annie Petsonk, international counsel for the advocacy group the Environmental Defense Fund, said the impasse over how to craft a new treaty could imperil less-controversial measures such as money to help developing countries cope with climate change.

“Often these things are considered as a package,” Petsonk said in a phone interview, adding that she was puzzled by the Obama administration’s resistance to a binding treaty. “Most parties here want that, and most parties were hoping the United States would support that."

This post has been updated since it was first published.