United Nations climate envoys may drop their plan to complete a binding global-warming agreement by the end of 2010, as two weeks of talks in Copenhagen overran their deadline with no framework to forge a treaty.

A draft agreement to be signed in the Danish capital omitted a requirement that nations adopt "one or more legal instruments" to fight global warming during a UN meeting planned in Mexico City in November. The 2010 limit was in an earlier draft today.

"The big obstacle is the gap between developed and developing countries: We're playing ping-pong," Haimoude Ould Ahmed, a senator from Mauritania, said in an interview in Copenhagen. "We'll have to prolong the talks into the night and tomorrow morning. We're worried. We had many hopes."

With a gulf remaining between China and the U.S., the biggest greenhouse-gas emitters, U.S. President Barack Obama scheduled a second meeting with Chinese Premier Wen Jiabao for 7 p.m., an hour after the planned close of the 193-nation summit.

The draft, obtained by Bloomberg News, retains several elements from its earlier version. One calls for containing the average global temperature to within 2 degrees Celsius (3.6 degrees Fahrenheit) compared with pre-industrial times.

Another provision of the "Copenhagen Accord," which lacks final approval, calls for the richest nations to provide climate aid to developing nations of $30 billion over the next three years and $100 billion annually by the end of 2020, a plan that has won endorsement by the U.S.

80 Percent Emissions CutThe proposal also seeks an 80 percent emissions-cut by rich countries by 2050 and stopped short of listing any goals for 2020.

Delegates said the summit, scheduled to end at 6 p.m. today, won't end until at least tomorrow. There was opposition by some of the 119 world leaders attending the conference to the draft text, because it isn't one of two official United Nations negotiating texts that are the product of two years of talks.

"The documents that were being worked on for two years were left there frozen, like the snow falling here in Copenhagen," Venezuelan President Hugo Chavez told reporters earlier today. "Now they're trying to bring a document out of nothing. We can't support or accept that which we don't know."

Earlier today, U.S. President Barack Obama met privately with Chinese Prime Minister Wen Jiabao for almost an hour. Wen later failed to attend a meeting between Obama and other world leaders, adding to speculation the world's two biggest emitters are far apart on an agreement to fight climate change.

Bolivian President Evo Morales also said his country "can't accept" the document. Chavez and Morales made their comments before the latest draft was published.

Temperature TargetThe new draft changes wording about a temperature target, saying nations should strive to keep warming to "below 2 degrees." Earlier the text said the rise in global temperatures "ought not to exceed 2 degrees." Neither draft specified the units, though envoys from the U.S., Europe and China have backed a target of 2 degrees Celsius (3.6 degrees Fahrenheit.)

Accepting 2 degrees "is to finish with all the islands in the world," Bolivia's Morals said.

Delegates put an "X" for the 2020 target, compared with 1990 levels in both the new and earlier drafts.

"This cannot be the outcome of Copenhagen: they're going to have to do a lot more work," Cindy Baxter, a spokeswoman for the environmental campaign group Greenpeace said earlier today in an interview in the Danish capital.

Envoys from 193 nations are trying to craft a declaration to conclude the talks, which are being attended by about 120 world leaders, including U.S. President Barack Obama, who repeated U.S. emissions pledges and financial aid today.

The draft text included provisions for a total of $30 billion in climate aid from rich to poor nations over three years, rising to $100 billion annually by 2020, a figure Obama said the U.S. supports.

European delegates and UN Framework Convention on climate Change Executive Secretary Yvo de Boer last month said the Copenhagen summit, the culmination of two years of negotiations, wouldn't produce a legally binding treaty to curb greenhouse gases, and that it should set a firm timeline to achieve one.

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