Delegates from nearly 200 countries are working overtime Saturday at a climate conference in South Africa, trying to reach a deal on fighting global warming.

Representatives are negotiating well past Friday's scheduled end to the two-week U.N. Framework Convention on Climate Change in Durban.

Delegates are evaluating a European Union proposal that calls for a second commitment period on the Kyoto Protocol, which legally binds governments to cut emissions. Under the so-called EU “roadmap,” a new commitment of at least five years must be implemented by 2020.

EU Commissioner for Climate Change Connie Hedegaard has been urging delegates to compromise on the proposal before time runs out.

But negotiators say they will not have enough time to format all of their concerns into the EU plan. Observers note the world's biggest polluters, including the United States, China and India, have not agreed on the plan.

The European Union has won support from an alliance of the world's poorest countries and small island nations, on more ambitious action from other countries.

The EU says it will not renew its emission reduction pledges under the Kyoto Protocol unless all countries are committed to controlling their emissions.

The United States says it will only pledge binding cuts if all major polluters make comparable commitments. China and India say their cuts should be less than developed nations. Those countries are not bound by the Kyoto Protocol.