WASHINGTON - By brokering a climate deal in Copenhagen a week ago, President Obama has committed himself to a more daunting task: pushing for comprehensive climate legislation in the Senate next year.

Although many senators, especially key Republicans, have shown little appetite for backing yet another ambitious bill in the aftermath of the polarizing health-care debate, it is clear that enacting legislation to cap the U.S. carbon-dioxide output and allow polluters to trade emission permits is essential to delivering on the pledges Obama made to other world leaders.

Obama told the Washington Post last week, "There is no doubt that energy legislation is going to be tough, but I feel very confident about making an argument to the American people that we should be a leader in clean-energy technology - that that will be one of the key engines that drives economic growth for decades to come."

White House spokesman Ben LaBolt said the fact that "countries like China and India set carbon-intensity targets for the first time in history" should bolster the administration's legislative effort.

Since taking office in January, Obama and his deputies have regarded international climate talks as a way to get the sorts of commitments from major emerging economies that would allow them to sell a cap-and-trade bill to skeptical lawmakers back home. As part of last week's accord, the four biggest greenhouse-gas emitters in the developing world - China, India, Brazil, and South Africa - agreed to list voluntary climate targets as part of an international registry and to allow third-party countries to scrutinize whether the four are making the emission cuts they say they are.

"That was the strategy all along," said Mark Helmke, a senior adviser to Sen. Richard Lugar (R., Ind.), whose vote could be critical to passing a climate bill. "In that context, it was a home run."

But it is unclear whether that achievement - which came at the expense of getting more ambitious overall climate targets and a clear deadline for a legally binding treaty next year - will translate into passage of the bill the administration is seeking.

Sen. Lisa Murkowski (R., Alaska), the top Republican on the Senate Committee on Energy and Natural Resources and another swing vote, called language in the Copenhagen deal allowing for verification of developing countries' carbon cuts "a very small step forward."

"The big question is whether the Senate, as a whole, can sit down and craft real bipartisan legislation that protects both the economy and the environment," she said. "We need to find ways to move forward in a bipartisan effort that makes sense for America, regardless of whether the rest of the world follows through or not."

In the wake of the health-care debate, winning Republican support for such a bill is crucial, even if it might mean adding provisions favored by the nuclear and oil industry, or scaling back the legislation's scope.

"I don't think the Senate has an appetite for another such epic, polarized legislative war this session," said Sen. Joe Lieberman (I., Conn.), who met Wednesday with Sens. John Kerry (D., Mass.) and Lindsey Graham (R., S.C.) to strategize on how to enlist support for a compromise climate bill they are writing.

The task becomes more difficult in an election year, when most Republicans and conservative thinkers are eager to attack a policy that will probably raise energy prices in the near term.

"In truth, emissions reductions, whether done by legislation, treaty or regulation for that matter, are ineffective and unpopular ideas," said Ben Lieberman, a senior policy analyst on energy and environment at the conservative Heritage Foundation.

Regardless of these obstacles, Obama has little choice but to press the issue. He and Secretary of State Hillary Rodham Clinton pledged in Copenhagen that the United States would help mobilize $100 billion in annual funding by 2020 to help poor countries cope with global warming. Administration officials said a significant portion of the U.S. contribution would come from carbon trading markets where polluters would have to buy emission allowances from the federal government and offset some of their emissions by investing in forestry projects overseas.

Michael Levi, a senior energy and environment fellow at the Council on Foreign Relations, said that although the administration need not put a cap-and-trade system in effect immediately, "their international credibility will suffer if they can't start putting mechanisms for cutting emissions and delivering on their financial goals relatively soon."

Environmentalists and some of their allies on Capitol Hill are confident that Obama is invested enough in the issue to focus on climate legislation next year. Kerry said there is "not a chance in hell" that there won't be a major push "after the president put American prestige on the line in Copenhagen."