The Environmental Protection Agency is expected to act for the first time to regulate carbon dioxide and other greenhouse gases, The New York Times reported on Wednesday, citing senior Obama administration officials.

EPA Administrator Lisa Jackson has asked her staff to review the latest scientific evidence and prepare documentation for a finding that greenhouse gas pollution endangers public health and welfare, the newspaper said.

There is wide expectation that Jackson will act by April 2, the second anniversary of a Supreme Court decision that found that EPA has the authority to regulate greenhouse pollution under the U.S. Clean Air Act.

In an interview with the Associated Press on Tuesday, she said the EPA will soon decide whether greenhouse gases are a danger to human health and welfare, the legal trigger for regulation under federal law.

"We are going to be making a fairly significant finding about what these gases mean for public health and the welfare of our country," Jackson said.

Jackson said the American people deserve an opinion, after years of the Bush administration not taking a position on the matter -- a track record that she referred to as a deafening silence.

"If EPA is going to talk and speak in this game, the first thing it should speak about is whether carbon dioxide and other greenhouse gases endanger human health and welfare," she said. "It is a very fundamental question."

Recent EPA decisions have hinted that the agency was leaning toward using the Clean Air Act to regulate the gases, a step the Bush administration refused to take despite prodding from the Supreme Court.

In his first week in office, President Obama directed the agency to review a decision by the Bush administration denying California and other states the right to control greenhouse gases from automobiles.

On Tuesday, the EPA announced it was reviewing a Bush policy that prohibits using the federal permit process to require new coal-fired power plants to install equipment to reduce carbon dioxide, the most prevalent greenhouse gas.

Jackson said Tuesday that the agency was now turning its attention to the broader question of regulation under the Clean Air Act as part of a series of steps it was taking to move toward what she called a carbon-constrained future. The federal law has been used since 1970 to curb emissions that cause acid rain, smog and soot.

In 2007, the Supreme Court ruled that it could be used to curb carbon dioxide and other greenhouse gases, but the Bush administration refused to use the law, saying it was the wrong tool.

Jackson took a different position Tuesday during one of her first interviews since winning Senate confirmation Jan. 23.

"It is clear that the Clean Air Act has a mechanism in it for other pollutants to be addressed," she said.

But Jackson also said the EPA would not act alone and regulation at the federal level would not prevent states from taking their own steps or preclude Congress from passing legislation to limit greenhouse gas emissions, something Democratic leaders on the Hill are already working on.

The United States is under pressure to take some action on global warming in advance of negotiations, scheduled for later this year in Copenhagen, on a new international treaty.

The Bush administration pulled out of the last treaty, the 1997 Kyoto Protocol, citing a lack of participation by developing countries and harm to the U.S. economy. In the late 1990s, during the Clinton administration, the Senate balked at ratifying the agreement.

The Associated Press contributed to this report.