The U.S. Environmental Protection Agency said on Tuesday it will reconsider a Bush administration rule to let new coal-fired power plants open without taking climate-warming carbon emissions into account.

Environmental leaders, who had petitioned the agency to overturn the Bush rule, hailed EPA's move as a step toward the regulation of carbon dioxide emissions and a departure from the Bush administration's stand on climate change.

EPA Administrator Lisa Jackson granted the environmental groups' request for reconsideration of the rule, and in a letter to the petitioners, called for an unspecified period of public comment before a new rule is put in place.

This will be a fair, impartial and open process that will allow the American public and key stakeholders to review this ... to comment on its potential effects on communities across the country, Jackson said in a statement. EPA's fundamental mission is to protect human health and the environment and we intend to do just that.

In the letter, Jackson also cautioned companies aiming to start construction on power plants not to rely on the Bush administration rule in seeking permission to build.

Today's victory is yet another indication that change really has come to Washington, and to EPA in particular, said David Bookbinder of the Sierra Club, one of three groups that called for the reconsideration.

This decision stops the Bush administration's final, last-minute effort to saddle President Obama with its do-nothing policy on global warming, Bookbinder said in a statement.

The Natural Resources Defense Council and the Environmental Defense Fund also called for the reconsideration.

ANOTHER DEPARTURE FROM BUSH ERA

It was the second time this month that the Obama administration has diverged from the Bush environmental position.

On Feb. 6, the EPA said it would reconsider whether to grant California and other states the authority to cut greenhouse gas emissions by new cars and light trucks, a request the Bush administration denied.

EPA's decision on coal-fired power plants follows more than a year of bureaucratic maneuvering at the end of the Bush administration over whether new plants must limit emissions of carbon dioxide, which contributes to climate change.

The maneuvering began soon after the April 2007 ruling by the U.S. Supreme Court that found EPA has the authority to regulate carbon emissions under the Clean Air Act. Since then, the Bush administration parried any attempts to regulate carbon dioxide as a pollutant.

On Nov. 13, 2008, EPA's own Environmental Appeals Board concluded that the agency had not adequately explained why a Clean Air Act provision on pollutants did not apply to carbon dioxide.

On Dec. 18, Bush administration EPA chief Stephen Johnson wrote a memorandum calling the appeals board's conclusions invalid.

The environmental groups sued to overturn the Johnson memo. EPA's Jackson let the memo stand, but noted that it is not the final word on the appropriate interpretation of the Clean Air Act requirements.

(Additional reporting by Tom Doggett; Editing by David Wiessler)

California U.S. George W. Bush