Countries leading the push for a Copenhagen treaty seemed to be resigned to failure – despite US legislation being approved in a key Senate committee, with most of them pointing the finger of blame Washington’s failure to make significant commitments on emissions cuts.

Negotiators said that the most that can be hoped for at Copenhagen is a political agreement on emissions cuts, while EU’s chief negotiator, Artur Runge-Metzger said a binding deal following that “should be done as early as possible ... three months, six months.”

"It is a Catch-22 situation," said Runge-Metzger. "People are waiting for each other so it is difficult to blame anyone. [But] the US position is significant in terms of the delay. Clearly the US has been slowing things down." UK officials told reporters that agreeing a detailed treaty is likely to take at least six months and "ideally no longer than a year" after Copenhagen.

A Japanese official said "unless it's agreed within six months after Copenhagen it will perhaps be the following year because of the U.S. mid-term elections." About a third of the U.S. Senate is up for re-election in November 2010.

Developing nations have become increasingly anger at what they perceive to be a failure by rich countries to take action on an issue which is affecting poorer countries disproportionately and African nations temporarily

"It seems that somewhere, someone decided 'let's shift gear, let's make sure we don't move so much'," said Bruno Sekoli of Lesotho, chair of the group of least developed nations.

Yvo de Boer, head of the U.N. Climate Change Secretariat, has said Copenhagen must at least set 2020 emissions reductions targets for rich nations including the US, agree actions by the poor to slow their rising emissions, and create mechanisms to raise billions in funding and oversee the funds.