By Louis Charbonneau

UNITED NATIONS (Reuters) – A key senator on Monday said the committee she leads should approve a bill to tackle global warming before a U.N. climate summit in December, and the U.S. energy secretary said he hoped the bill could be signed into law by then.

“I believe we will get this bill out of my committee soon,” Senator Barbara Boxer, who chairs the Environment and Public Works Committee, told reporters after a meeting with U.N. Secretary-General Ban Ki-moon.

“Certainly before Copenhagen, and we’re hoping maybe to even have it on the floor (of the Senate),” she said.

Energy Secretary Steven Chu was much more optimistic than Boxer when asked when the legislation could become law. He told reporters in London he remained hopeful President Barack Obama would be able to sign a domestic climate change bill before the Copenhagen conference.

“Whether there will be a bill on the president’s desk and he’ll sign it, I’m hopeful it will be,” he told reporters on the sidelines of a meeting on clean coal technologies.

Boxer co-authored the Senate Democrats’ 800-page draft bill on climate change with Foreign Relations Committee Chairman John Kerry.

Boxer said Ban, who has been lobbying U.N. member states to agree on a deal to fight global warming in Copenhagen, had asked Boxer about the timeline for the U.S. legislation.

Obama, in a sharp reversal from his predecessor George W. Bush, has vowed to impose mandatory limits on the emission of climate-warming greenhouse gases and made tackling global warming a signature issue of his administration.

The Bush administration had opposed mandatory emission limits, arguing that they would damage the competitiveness of U.S. industry.

GREENHOUSE GASES

The Boxer-Kerry draft bill would reduce U.S. industry emissions of carbon dioxide and other greenhouse gases by 20 percent by 2020, a smaller reduction than European Union countries have pledged.

Their proposal embraces central elements of a climate change bill passed in June by the Democratic-led House of Representatives.

The two senators face a tough fight to win over skeptical Republicans and some Democrats to get their proposal passed, but their prospects improved on Sunday when a Republican senator broke ranks with his party to outline a compromise with Democrats.

Republican Senator Lindsay Graham and Kerry wrote in an opinion piece in The New York Times that they believed they could pick up enough support to pass a wide-ranging bill to limit carbon emissions.

“We refuse to accept the argument that the United States cannot lead the world in addressing global climate change,” Graham and Kerry wrote. “We are also convinced that we have found both a framework for climate legislation to pass Congress and the blueprint for a clean-energy future.”

Graham is one of a few dozen fence-sitters who Kerry and Boxer have been courting in order to amass the 60 votes needed for passage in the 100-member Senate..