Diplomats from the world`s biggest greenhouse gas polluters including the United States, China and India are set to take part in a forum on Monday at the U.S. State Department aimed at getting a U.N. agreement to curb global warming. The two-day meeting of so-called major economies is meant to jump-start climate talks in advance of a December deadline, when the international community meets in Copenhagen to find a follow-up agreement to the Kyoto Protocol, which limits climate-warming greenhouse emissions and expires in 2012. Secretary of State Hillary Clinton is scheduled to make opening remarks. Participants are expected to discuss technology cooperation and other issues. The major economies include Australia, Brazil, Britain, Canada, China, the European Union, France, Germany, India, Indonesia, Italy, Japan, Korea, Mexico, Russia, South Africa and the United States. Denmark, the host of the December meeting, also was invited. Environmentalists and others see U.S. commitment to fighting climate change as key to any global pact. "Without U.S. leadership, a global warming agreement in Copenhagen will be largely out of reach," said Jake Schmidt of the Natural Resources Defense Council activist group. President Barack Obama has stressed the link between fighting climate change and helping the struggling economy, and called the meeting to relaunch the major economies process begun by his predecessor George W. Bush. The Bush team`s efforts drew skepticism from many participants and were seen as a distraction from the main U.N. negotiations on climate change.