WASHINGTON -- Climate change, it seems, is no longer a dirty phrase for Democrats to disavow.

President Barack Obama promised in his second inaugural address to respond to climate change, casting it as a moral obligation and warning that failing to take action "would betray our children and future generations." It’s not just a responsibility to his fellow Americans, Obama said Monday, but to "all posterity."

Persuading Americans that they should care about climate change _ or have a duty to do so _ is one thing. Actually doing something about the emissions that contribute to rising sea levels, sooty skies and melting Arctic sea ice is a far more complex task. Despite Obama’s pledges Monday, the White House was scant with details this week, saying only that it’s pursuing action under the existing regulatory framework.

Given that sweeping legislation to cap greenhouse gas emissions not only failed in his first administration, but also fell apart in a way that may have damaged the fortunes of future climate-related legislation, the White House has challenging work ahead. It must negotiate a polarized Congress, regional energy interests and pressure from big polluters and the influential energy sector.

The industry is bracing for a fight. Some groups, such as the National Association of Manufacturers, have challenged the Environmental Protection Agency’s authority to regulate greenhouse gases under the Clean Air Act.

They’ll continue to argue that regulation of greenhouse gases should come from Congress, not the executive branch, said Ross Eisenberg, the vice president of energy and resources policy for the association. International emissions and the economic consequences of U.S. regulatory decisions need to be factored in, too, he said.

"If you put constraints on one economy, and other economies you’re competing with don’t have it, you’re constraining growth and putting an additional cost on the manufacturing process that your competitors don’t have," he said.

Congress has shown that it remains divided over what environmentalists say is one key indicator of how the second Obama administration will approach emissions. A majority of senators urged the president this week to approve the Keystone XL pipeline, which would bring oil to the United States from the Canadian tar sands. The administration has twice delayed a decision, which is pending environmental approval at the State Department. Sen. John Kerry, D-Mass., gave no indication Thursday in his confirmation hearing to become the next secretary of state how he’d move on the decision, but he said he’d make sure that climate change issues are taken into consideration.

Meanwhile, the governor of Nebraska signed off this week on the pipeline’s path through the state.

Yet those who favor action on climate change said they were hopeful, and they’ve been drawing up plans for the White House that they think match the rhetoric of the inaugural address. Obama’s re-election was the first step, said Bob Deans, a spokesman for the Natural Resources Defense Council. The next step, he and other environmentalists said, is for the president to act on his pledge.

"In November, the country went with the guy who said it’s a threat," Deans said. "Is that a mandate? I don’t know. But without question it’s a historic opportunity. And on Monday, the president showed he’s very serious about taking advantage of that opportunity."