US President Barack Obama hopes his presence at the United Nations Climate Change Summit in Copenhagen can help nations reach an agreement, White House spokesman Robert Gibbs said Wednesday.

Obama will arrive in Copenhagen on the last day of the UN Climate Change Conference on Dec. 18. The meeting aims to map out a comprehensive international arrangement for the fight against climate change over the period 2012-2020.

Gibbs reiterated that any deal at the Copenhagen talks should be verifiable to make sure all parties are living up to their agreements on reducing carbon emissions.

On Tuesday, US Secretary of State Hillary Clinton also expressed her opinion in the "International Herald Tribune" that success in Copenhagen demanded that all major economies agree to a system that is transparent and trusted.

However, according to the Bali Roadmap, it is developed countries whose targets of emissions reduction must be "measurable, reportable and verifiable." Meanwhile, developing countries' efforts toward sustainable development should be supported in a "measurable, reportable and verifiable" way in terms of technology, finance and capacity building.

Some developing countries argued that the Bali Roadmap must be fully respected and that it is not necessary for the voluntary emissions reduction actions taken by developing countries to be "measurable, reportable and verifiable."