The US will pledge to cut its greenhouse gas emissions by 17 percent by 2020 at a U.N. climate change meeting in December, the White House said Wednesday.
Obama's negotiating position for the talks in Copenhagen has been hampered by slow progress on a climate bill in the U.S. Senate.
The House passed a bill that sets a 17 percent reduction target for emissions by 2020 from 2005 levels. A Senate version aims for a 20 percent cut.
The European Union is pressing for more aggressive cuts and has pledged a 20 percent drop in its emissions compared to 1990 levels.
The US pledge came as President Obama decided to go to Copenhagen next month to participate in the long-anticipated, high-stakes global climate summit.
The president will attend the summit on Dec. 9 before heading to Oslo to accept the Nobel Peace Prize, the official said. Obama's attendance had been in question until now.
The official spoke on the condition of anonymity because the formal announcement has not been made.
The conference had originally been intended to produce a new global climate change treaty on limiting emissions of greenhouse gases that would replace the 1997 Kyoto Protocol. However, hopes for a legally binding agreement have dimmed lately, with leaders saying the summit is more likely to produce a template for future action to cut emissions blamed for global warming.
At least 65 world leaders will attend the summit, but unlike Obama, most are expected to attend the final days of the Dec. 7-18 conference.
Yvo de Boer, U.N. climate treaty chief, told reporters in Bonn Wednesday, "I think it's critical that President Obama attend the climate change summit in Copenhagen. The world is very much looking to the United States to come forward with an emission reduction target and contribute to financial support to help developing countries."
While Obama himself tried to tamp down expectations during his eight-day trip to Asia earlier this month, he also called on world leaders to come to an agreement that has "immediate operational effect" and is not just a political declaration.
Administration officials said earlier this week that the U.S. will present a target for reducing carbon dioxide emissions at the summit. The development came as the European Union urged the United States and China to deliver greenhouse gas emissions targets at the summit, saying their delays were hindering global efforts to curb climate change.
The administration has indicated for nearly a year that it would eventually come up with specific targets for quick reductions in pollution that causes global warming, as part of international negotiations. Those targets will soon be made public, officials said earlier this week, and will reflect the unfinished state of legislation on Capitol Hill.
A House-passed bill would slash heat-trapping pollution by 17 percent from 2005 levels by 2020. A Senate bill seeks a 20 percent reduction over the next decade, but that number is likely to come down to win the votes of moderate Democrats.
This will be Obama's second trip to Denmark this year. He made short trip to Copenhagen on Oct. 2 to make a vain pitch for 2016 Summer Olympics in Chicago during a meeting of the International Olympic Committee.