WASHINGTON - Stymied in Congress, the Obama administration is moving unilaterally to reduce greenhouse-gas emissions from power plants and oil refineries, announcing plans to develop new standards over the next year.

Environmental Protection Agency administrator Lisa Jackson, in a statement posted on the agency's website late Thursday, said the aim was to better cope with pollution contributing to climate change.

"We are following through on our commitment to proceed in a measured and careful way to reduce [greenhouse gas] pollution that threatens the health and welfare of Americans," Jackson said in a statement. She said emissions from power plants and oil refineries account for about 40 percent of the greenhouse gas pollution in this country.

President Obama said after the midterm elections that he was disappointed Congress hadn't acted on legislation achieving the same end, signaling that other options were under consideration.

Legislation that would put a limit on heat-trapping greenhouse gases and allow companies to buy and sell pollution permits under that ceiling - a system known as "cap and trade" - stalled in the Senate earlier this year after narrowly clearing the House. Republicans assailed it as "cap and tax," arguing that it would raise energy prices.

But the Senate in late June rejected, 53-47, a challenge brought by Alaska Republican Lisa Murkowski that would have denied the EPA the authority to move ahead with the rules.

Jackson noted in Thursday's statement that several state and local governments and environmental groups had sued EPA over the agency's failure to update or publish new standards for fossil-fuel-burning plants and petroleum refineries. Thursday's announcement came in connection with a settlement of the states' lawsuit.

The EPA was at the center of the battle in Congress over climate-change policy, especially in the wake of a 2007 Supreme Court ruling that authorized the agency to regulate heat-trapping gases.

"While there will be attacks on [EPA's] authority, it is important that there not be any surrender on EPA's ability to do the job," Trip Van Noppen, president of the environmental group Earthjustice, said earlier this year.

The EPA moved against climate change on another front earlier this year, issuing the first-ever federal guidelines for reducing greenhouse emissions from industrial sources.

On Nov. 10, the agency sent new guidelines to states. It suggested that dirty fuel used to power oil refineries be replaced with cleaner alternatives, and it called for more efficient electricity and energy use with existing nuclear power plants.

Jackson's announcement Thursday said that under an agreement associated with the lawsuit, the EPA would propose standards for power plants in July and for refineries in December, and would issue final standards in May and November 2012.

The agency plans "listening sessions" with representatives of business and local governments ahead of the formal rulemaking process.