US President Barack Obama is to unveil new rules for coal-burning power plants aimed at dramatically cutting emissions that contribute to global warming.
The proposals reportedly seek to cut carbon pollution from nearly 1,600 power plants by 30% by 2030.
China and India are among the nations that have made similar commitments to stem global warming.
But critics argue the new US rules will cause power plants to close and electricity prices to rise.
'I intend to make sure America is out front in a global framework to preserve our planet,' Mr Obama said in a speech last week.
'American influence is always stronger when we lead by example. We cannot exempt ourselves from the rules that apply to everyone else.'
By Matt McGrath, BBC environment correspondent
The use of shale gas, fracked from huge reserves in Pennsylvania, Texas and elsewhere has already helped the US to curb its carbon. But coal is still a major factor in energy production, accounting for about 40% of electricity. After the proposals are announced, there will be a year-long consultation, followed by another 12 months in which states will have to submit their plans for review. Despite these delays, international observers believe the new proposals will help re-establish the credibility of the US on the international stage. US 'to take significant step' on climate
Details of the plan have yet to be revealed, but the Wall Street Journal and New York Times, quoting sources briefed on the plan, said the Obama administration would seek a 30% cut in carbon emissions by 2030 as compared with 2005 levels.
Administration officials have described the new rules as a step toward achieving a pledge Mr Obama made in his first year in office to make sizeable cuts in US carbon emissions by 2020.
The Democratic president has been unable to persuade Republicans in Congress to act on climate change legislation. A 2010 Democratic effort to pass a bill limiting carbon-dioxide emissions and allowing companies to buy and sell permits to pollute was blocked by Senate Republicans.
Now, the Obama administration will rely on a 2007 US Supreme Court ruling that gave the Environmental Protection Agency, part of the executive branch of the US government under Mr Obama's control, the ability to regulate carbon dioxide under the Clean Air Act.
Once the new guidelines are issued, it will be left to each state to develop a strategy for meeting them.
These may include increasing nuclear or solar power, switching to natural gas, or moving towards an emissions-trading plan, known as cap-and-trade.