Obama: 'Meaningful breakthrough' on climate change

Obama said the five nation's pledges would be "subject to an international consultation" that will allow each country to "show the world what they're doing."

China's resistance to a verification mechanism had been one of the major sticking points for the U.S. during the two weeks of climate negotiations here.

"We're in this together, and we'll know who is meeting and not meeting the mutual obligations that are set forth," Obama said.

As for the U.S., he said, "We will not be legally bound by anything that took place here today," pre-emptively answering congressional critics who had warned repeatedly that Congress will have the final say in any U.S. emission reduction commitments.

The deal also would provide a mechanism to help poor countries pay for dealing with climate change.

The president had planned to spend only about nine hours in Copenhagen as the summit wrapped up after two weeks. But, as an agreement appeared within reach, he added extended his stay by more than six hours to attend a series of meetings aimed at brokering a deal.

"We are running short on time," Obama had told the summit as the clock was running out on its final day. "There has to be movement on all sides."

He met with other leaders, including Chinese Premier Wen Jiabao.

Obama and Wen met twice — once privately and once with other world leaders present — in hopes of sweeping aside some of the disputes that have barred a final deal. Officials said the two leaders took a step forward and directed negotiators to keep working.