Copenhagen , Denmark ( CNN ) -- U.S. Secretary of State Hillary Clinton on Thursday warned participants in the climate change conference in Copenhagen that they are `` running out of time '' to reach an agreement on what to do about global warming . Critics say those attending the United Nations Climate Change Conference , which began December 7 , have made little or no headway toward developing a plan . U.S. officials in Copenhagen and at the White House confirmed that talks broke down Wednesday after the Chinese rejected American demands that they commit to transparency regarding their emissions reductions . Without mentioning China by name , Clinton said their continued refusal would be `` kind of a deal breaker for us . '' The uncertainty over whether a deal could be reached before talks end Friday led to speculation that President Barack Obama might not travel to Copenhagen as planned , but White House spokesman Robert Gibbs told reporters he would leave Thursday evening . `` We all know there are real challenges that remain in the hours left to these negotiations , '' Clinton said . `` And it is no secret that we have lost precious time in these past days . In the time we have left here , it can no longer be about us versus them . `` We all face the same challenge together , '' she added . `` We 're running out of time . It 's unfortunate that there have been problems with the process , difficulties with certain parties being willing to come to the table , all kinds of discussions and disagreements , sometimes about the past rather than about the future . '' Without mentioning China by name , Clinton said that nation 's continued refusal to come to the table would be `` kind of a deal breaker for us . '' Gibbs said the Chinese `` balked '' at the `` strong transparency requirement , '' and he `` hoped they would reconsider . '' `` The president is going to travel in hopes of making progress for a strong operational agreement , '' Gibbs said . `` There are no changes in the president 's plans . '' The agreement Obama is hoping for out of Copenhagen would not be a treaty , nor would it be legally binding . Gibbs acknowledged it would be `` a political agreement that would lead to a treaty '' later . The last time the president traveled to Copenhagen -- in October to try to win the 2012 Olympic bid for Chicago -- he came back empty-handed . `` Coming back with an empty agreement would far worse , '' Gibbs said Thursday . Clinton said the United States is concerned about the ability of needy nations to do their part . The United States is willing to work with other countries to raise $ 100 billion by 2020 to address the climate-change needs of developing nations , she said . She told delegates that the United States already has joined an effort to provide more immediate funding that would reach $ 10 billion in 2012 . `` After a year of diplomacy , we have come to Copenhagen ready to take the steps necessary to achieve a comprehensive and operational new agreement that will provide a foundation for long-term , sustainable economic growth , '' Clinton said . `` We have now reached the critical juncture in these negotiations . I understand that the talks have been difficult . I know that our team , along with many others , are working hard and around the clock to forge a deal , '' she said . `` But the time is at hand for all countries to reach for common ground and take an historic step that we can all be proud of . '' Clinton 's announcement was `` enormously encouraging , '' Tim Flannery , an internationally known zoologist , conservationist and explorer , said on CNN 's `` Amanpour . '' Clinton proposed several core elements that should be included in any plan : decisive national actions ; an operational accord `` that internationalizes those actions '' ; technical and other assistance for needy nations that are `` the most vulnerable and least prepared to meet the effects of climate change ; and standards of transparency that provide credibility to the entire process . '' `` The world community should accept no less , '' she added . Kandeh Yumkella , director-general of the U.N. Industrial Development Organization , said on `` Amanpour '' he is optimistic that leaders can strike a deal before the conference ends . `` Compared to yesterday , what we have now is that the negotiators have hunkered down , '' he said . `` They 're actually in drafting committees . '' Flannery agreed . `` If the U.S. can commit to another couple of percent in terms of cuts ( in emissions ) , if the Chinese can increase their efficiency gains by 5 percent , that 'll probably be enough to bring the Europeans on board for a 30 percent target , and then we 'll be there . '' Meanwhile , British Prime Minister Gordon Brown , who suggested the initial estimate of about $ 100 billion a year by 2020 to reduce emissions , urged leaders Thursday to reach an agreement that would limit `` long-term , global temperature increases '' to no more than 2 degrees . According to the 10 Downing Street Web site , Brown told the conference that wealthier countries must commit to provide immediate funding for developing countries to reach such a goal . He recommended that financing start in January , with nations providing $ 10 billion a year by 2012 . He called on developing countries to commit to ambitious mitigation actions to handle climate change . `` To the developed world I say : Environmental action is the most powerful engine of job creation in an economy urgently in need of millions of new jobs . `` To the developing world I say : The technology now exists to gain the dividends of a high-growth economy without incurring the damage of a high-carbon economy . `` And to all nations I say : It is not enough for us to do the least we can get away with when history asks that we demand the most of ourselves . ''
U.S. joins an effort to mobilize `` fast-start '' funding for developing counties . The White House has been pushing Congress and the administration to provide more money in order to help states deal with a growing number of undocumented immigrants who are living here illegally. U.S. President Barack Obama is expected to join the talks Friday . Japan , EU pledge more than $ 20 billion in climate aid to developing nations .