After two years of tough U.N. climate talks often pitting the world's rich against the poor, negotiators said Friday that a new global agreement now rode on industrial nations pledging profound emissions cuts at next month's conference in Copenhagen.

Negotiators from industrial nations including the United States on Friday said 11th-hour promises are possible and a global warming pact can be reached.

But developing countries complained that pledges so far were nowhere near enough to avoid climate catastrophe, and that world leaders need to participate in the conference to cut a meaningful deal.

"Part of the frustration is that a deal is so close ... all the elements are there," said Kevin Conrad, the delegate from Papua New Guinea. "But it's absolutely conceivable for senior people to come together and spend a week and clean all this up."

The United States was universally seen as the lynchpin to a Copenhagen deal, but it has been unable to present its position or pledge emissions targets because of the slow