He was speaking as European leaders urged the US Congress to take action on climate change ahead of next month's high-stakes summit.

Obama said they discussed climate change "extensively and all of us agreed that it is imperative for us to redouble our efforts in the weeks between now and the Copenhagen meeting to assure that we create a framework for progress in dealing with (a) potential ecological disaster."

European Commission head Jose Manuel Barroso, who was also visiting Washington, said earlier Tuesday he was "worried" by the lack of progress in climate negotiations ahead of the December 7-18 climate meeting in Copenhagen.

The summit in the Danish capital has been set up to seal a treaty to succeed the landmark Kyoto Protocol, whose obligations to cut carbon emissions expire in 2012.

Barroso said a meeting next year in Mexico could finalize a treaty but Copenhagen was needed to come up with the framework of the deal, and that the world's largest economy in particular should take a lead role.

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