A senior administration official, speaking to ABC News, heralded what he called a "significant breakthrough" at the United Nations Climate Change Conference in Copenhagen this afternoon.
President Barack Obama, Chinese Premier Wen Jiabao, Indian Prime Minister Manmohan Singh and South African President Jacob Zuma have agreed to a political "accord" that the official said will "provide the foundation for an eventual legally binding treaty."
In the accord, the official said, "nations will list their actions and stand behind them."
World leaders were looking to President Obama to help break a deadlock at the climate conference in Copenhagen, but prospects had looked bleak as White House officials indicated that Chinese officials were refusing to budge on their refusal to allow a transparent verification system, a stance that would have made a deal difficult to achieve.
The original goal of the climate change conference was a legally binding international treaty reducing greenhouse gas emissions worldwide, but with China hesitant to commit to serious greenhouse gas emission cuts, it became clear months ago that would not happen.
Leaders from more than 190 countries have spent the last two weeks working on a more informal climate change agreement, but that might be out of reach too.
Obama scheduled a second private, one-on-one meeting with Chinese Premier Wen Jibao to make a final push for a deal but the meeting did not take place. The U.S. president shifted his schedule around in Copenhagen to meet with world leaders.
Speaking to attendees on the final day of the conference, the president expressed his frustration at the stalemate.
"We are running short on time," Obama said. "There has to be movement on all sides."
Obama met with Jibao for nearly an hour earlier today to press the case that China needs to allow for transparency.
Obama and Wen directed their negotiators to work on a bilateral basis and with negotiators from other countries to see if an agreement can be reached here.
But a senior White House official in Copenhagen told ABC News the Chinese are holding their ground.
"We've done what we can here," the official said."The Chinese are dug in on transparency and are refusing to let people know they're living up to their end of the agreement."
"The president's priority is to make our economy far more focused on a clean energy economy that creates jobs," the official said. "He is here to work constructively and participate in hoping to get an international accord. But not getting one here won't change wanting to transform our economy to create the new foundation he's talked about."
Speaking to conference attendees, Obama addressed China's resistance.
"I don't know how you have an international agreement where we all are not sharing information and making sure we are meeting our commitments," he said. "That doesn't make sense. It would be a hollow victory."
Earlier today, Obama pushed for transparency, saying publicly that "we must have a mechanism to review whether we are keeping our commitments, and to exchange this information in a transparent manner. These measures need not be intrusive, or infringe upon sovereignty. They must, however, ensure that an accord is credible, and that we are living up to our obligations. For without such accountability, any agreement would be empty words on a page."
He added that the offer was on the table "if -- and only if -- it is part of the broader accord" including transparency.
The White House had hoped for an agreement before the president's high-stakes visit, but negotiations had been doomed to failure even before the conference began. In Copenhagen, negotiators worked through the night and met for hours behind closed doors in the hopes of reaching some sort of an agreement, with U.S. officials working quickly to reach a compromise before Obama's arrival.
President Obama Tries to Build Momentum in Copenhagen
In the last-minute push, even Secretary of State Hillary Clinton made an unscheduled appearance to urge on her international counterparts.
China has been hesitant to commit to a deal where it would be open to scrutiny by the international community. Leaders from the country have balked at measures to allow international monitors to verify emissions cuts that might be agreed to in the deal.
In the last 24 hours, officials say China had softened its opposition to verification of emissions reductions. Clinton announced Thursday that the United States will contribute to a $100 billion fund by 2020 to help poor countries cope with climate change, but that financial help is conditional on China relenting on verification, a move that could exert pressure on China.
But China and the United States still appear to be divided on the issue of verification.
The notion that the success of the climate agreements may hinge on the United States and China has frustrated leaders of some developing countries.
Speaking as the voice of the developing world, Brazilian President Lula da Silva gave a passionate speech where he scolded the developed world for not negotiating on climate change in good faith with poorer nations. He also said this conference is not about climate change, but about economic opportunities for the developing world.
With an array of challenges the president has to confront at home -- from health care to unemployment to the economy -- the president is putting his prestige at stake, both at home and abroad, to fly to Copenhagen and seal a deal on an issue that lacks the support of China, one of the biggest polluters in the world.
The U.S. president usually goes on trips like this when an agreement has already been worked out, but the White House says it is not a surprise that Obama went. His job as a leader, sources say, is to lead and that's what he wants to do in Copenhagen.
Obama's schedule is fluid at this point. The president was scheduled to meet with Rasmussen first thing upon arrival in Copenhagen before the climate change summit sessions, but instead, he went straight to a multilateral meeting, which included leaders from the European Union, India, Russia and Brazil.
When asked how long Obama will stay if there is no deal, a White House official said the "intention" is for the president to be Copenhagen only today.
Obama, whose Nobel Peace Prize win was partially attributed to his efforts on climate change, does not only face the skepticism of an international audience, but even his supporters back home. If he didn't go to Copenhagen, he would upset his liberal base.
It remains unclear where there will be a legally binding international treaty reducing greenhouse gas emissions worldwide, as had been the original goal of the conference. What leaders are hoping at this point is to have a more informal agreement that can be built upon down the road.
President Obama Stressed Urgency at Copenhagen
Addressing world leaders earlier today, Obama stressed the urgency of coming together on a deal and raised the deflating prospect of a deal.
"While the reality of climate change is not in doubt, I have to be honest, I think our ability to take collective action is in doubt right now and it hangs in the balance," Obama said at a plenary session at the United Nations summit.
"This is not a perfect agreement, and no country would get everything that it wants," the president said. "But here is the bottom line: we can embrace this accord, take a substantial step forward, and continue to refine it and build upon its foundation. We can do that, and everyone who is in this room will be a part of an historic endeavor, one that makes life better for our children and grandchildren."
Obama outlined three key elements that must be in the final agreement. First, all major economies must commit to reducing their emissions. Second, there must be a transparent review to ensure nations are keeping their commitments to reduce emissions, and thirdly, there needs to be financing to help developing nations adapt to these new standards.
What world leaders do agree on are the stakes. With unprecedented urgency, a chorus of leaders have delivered the same warning -- the planet is already damaged by climate change and countries need to step up to confront this challenge.
"We have a moral obligation towards future generations," said Prime Minister of Denmark Lars Lokke Rasmussen.
UK Prime Minister Gordon Brown described the stake in apocalyptic terms Thursday.
"Without common action, extreme temperatures will create a new generation of poor with climate change refugees driven from their homes by drought, climate change evacuees fleeing the threat of drowning, the climate change hungry desperate for lack of food," Brown said. "Hurricanes, floods, typhoons and droughts that were once all regarded as the acts of an invisible god are now revealed to be also the visible acts of man."
ABC News' Karen Travers, Kirit Radia and Viviana Hurtado contributed to this report.