Obama lobbied recalcitrant Democrats by phone from the White House as the debate unfolded across several hours, and Al Gore posted a statement on his Web site saying the measure represents "an essential first step towards solving the climate crisis." The former vice president won a Nobel Peace Prize for his work drawing attention to the destructive potential of global warming.

But Rep. John Boehner, the House Republican leader, used an extraordinary one-hour speech shortly before the final vote to warn of unintended consequences in what he said was a "defining bill." He called it a "bureaucratic nightmare" that would cost jobs, depress real estate prices and put the government into parts of the economy where it now has no role.