U.S. Secretary of State Hillary Rodham Clinton will arrive in Copenhagen on Thursday to attend the final days of a UN summit on climate change in a last push to get an international agreement on reducing greenhouse gases, the State Department confirmed on Wednesday. Ms. Clinton will join the discussion a day ahead of President Barack Obama, who is scheduled to arrive on Friday and is eager to show that the U.S., after years of downplaying the threat posed by global warming, is serious about reaching an accord. She and the president decided that she could play a useful role in helping close gaps in our climate talks there by travelling to Copenhagen and personally participating, spokesman Ian Kelly said. Nearly 200 countries are participating in the talks, and 119 heads of state are expected to attend the last day of the meeting that began Dec 7. But progress has been slow and some leaders and officials have expressed frustration about the pace towards reaching a deal. The Obama administration has been unwilling to go as far as European Union nations would like to curb greenhouse gas emissions chiefly blamed for global warming. Other countries like China and India, whose economies are growing rapidly, have been reluctant to sign onto tougher standards designed to limit climate change. The conference has been met with thousands of protesters and resulted in clashes with police. The top UN official for climate change, Yvo de Boer, expressed optimism Wednesday that a pact was within reach, but cautioned the next 24 hours are absolutely crucial and need to be used productively. The 12-day conference aims to slow global warming by imposing huge greenhouse gas emission cuts on rich nations and a massive transfer of money to poor nations who bear the brunt of climate change. But representatives have been unable to agree on how sharply to slow global warming, by how much rich nations should cut emissions, and how much money should be given to poor nations suffering from the effects of global warming.