WASHINGTON - President Obama made addressing climate change the most prominent policy vow of his second Inaugural Address on Monday, setting in motion what Democrats say will be a deliberately paced but aggressive campaign built around the use of his executive powers to sidestep congressional opposition.

"We will respond to the threat of climate change, knowing that failure to do so would betray our children and future generations," Obama said at the start of eight sentences on the subject, more than he devoted to any other specific area. "Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms."

The central place he gave to the subject seemed to answer the question of whether he considered it a realistic second-term priority. He devoted scant attention to it in the campaign and has delivered a mixed message about its importance since the election.

Obama is heading into the effort having extensively studied the lessons from his first term, when he failed to win passage of comprehensive legislation to reduce emissions of the gases that cause global warming. This time, the White House plans to avoid such a fight and instead focus on what it can do administratively to reduce emissions from power plants, increase the efficiency of home appliances and have the federal government itself produce less carbon pollution.

Action by the EPA

Obama's path on global warming is a case study in his evolving sense of the limits of his power and his increased willingness to work around intense conservative opposition rather than seek compromise. After coming to office four years ago on a pledge to heal the planet and turn back the rise of the seas, he is proceeding cautiously this time, Democrats said, intent on making sure his approach is vetted politically, economically and technologically so as not to risk missing what many environmental advocates say could be the last best chance for years to address the problem.

The centerpiece will be action by the Environmental Protection Agency to clamp down further on emissions from coal-burning power plants under regulations still being drafted -- and likely to draw legal challenges.

The administration plans to supplement that step by adopting new energy efficiency standards for home appliances and buildings, a seemingly small advance that can have a substantial impact by reducing demand for electricity. Those standards would echo the sharp increase in fuel economy that the administration required from automakers in the first term.

The Pentagon, one of the country's largest energy users, is also taking strides toward cutting use and converting to renewable fuels.

Obama's aides are planning those steps in conjunction with a campaign to build public support and head off political opposition in a way the administration did not the last time around. But the White House has cautioned environmental activists not to expect full-scale engagement while Congress remains occupied by guns, immigration and the budget.

The president's emphasis on climate change drew fire from conservatives. Tim Phillips, president of Americans for Prosperity -- a group financed by the Koch brothers, who made a fortune in refining and other oil interests -- criticized the speech. "His address read like a liberal laundry list with global warming at the top," he said. "Americans have rejected environmental extremism in the past and they will again."

Still, Obama has signaled that he intends to expand his own role in making a public case for why action is necessary and why, despite the conservative argument that such changes would cost jobs and leave the United States less competitive with rising powers like China, they could have economic benefits by promoting a clean-energy industry.

Emissions are declining

Those remarks stood in contrast to Obama's comments at his first post-election news conference, when he said he planned to convene "a wide-ranging conversation" about climate change and was vague about action. He is also expected to highlight his plans in his State of the Union address next month and in his budget plan soon afterward.

Beyond new policies, the administration seeks to capitalize on the surge of natural gas production in the past few years. As a cheaper and cleaner alternative to coal, natural gas gives the administration a chance to argue that coal is less economically attractive and a greater source of harmful emissions.

After the defeat in 2010 of legislation that would have capped carbon emissions and issued tradable permits for emissions, Obama turned to regulation and financing for alternative energy. Despite the lack of comprehensive legislation, emissions have declined about 10 percent since he took office, a result of the economic slowdown and of energy efficiency moves by government and industry.

The administration is already discussing with congressional Democrats how to head off a Republican counterattack on the new regulations. Democrats are paying particular attention to the likelihood of Republicans employing a little-used procedure to block new regulations with a simple majority vote.