WASHINGTON -- The Environmental Protection Agency yesterday said it couldn't propose any regulation of greenhouse gases because the issue was too complex, and there were too many objections from other federal agencies.

The Bush administration consistently has objected to mandatory limits on the heat-trapping gases that cause global warming. The EPA's decision to issue a 588-page report that calls for 120 days of public comment means that any regulatory action will be up to the next administration.

The Supreme Court ruled more than a year ago that the EPA must determine whether greenhouse-gas emissions from motor vehicles harm human health and welfare, and, if so, devise ways to regulate them under the Clean Air Act. The EPA document yesterday didn't make any policy decision. It contains EPA staff recommendations about regulation and objections to them raised by the White House and agencies such as the departments of Energy, Transportation and Agriculture.

EPA Administrator Stephen Johnson yesterday said that if the EPA regulated greenhouse-gas emissions from vehicles, that could trigger the regulation of emissions from all other sources of manmade greenhouse-gas pollution. The result, he said, could be "an unprecedented expansion of EPA authority that would have a profound effect on virtually every sector of the economy and touch every household in the land."

Scientists in the United States and worldwide have reached a strong agreement that manmade greenhouse gases, especially carbon dioxide from the burning of fossil fuels, is causing the Earth's average temperature to rise, and that, unless sharp cuts are made in these emissions, increasing warming could lead to catastrophic changes in the next century -- including extensive flooding of coastal areas, the spread of diseases and mass extinctions of plants and animals.

The EPA previously told the Bush administration that greenhouse gases endangered human health, but the administration didn't accept that finding or allow it to be made public.

Susan Dudley of the White House Office of Management and Budget said in a letter to Mr. Johnson that the EPA's draft of proposed rules raised so many concerns that it couldn't be accepted as administration policy, but that consensus wasn't necessary for further discussion.

Mr. Johnson told reporters that the EPA's staff "has done an outstanding job making a square peg fit into a round hole." But he added that he thought that the Clean Air Act was "ill-suited for the task of regulating global greenhouse gases."

"Based on the analyses to date, pursuing this course of action would take decades and inevitably result in a very complicated and likely convoluted set of regulations. If our nation is truly serious about regulating greenhouse gases, the Clean Air Act is the wrong tool for the job," Mr. Johnson said.

"EPA is publishing this notice today because it is impossible to simultaneously address all the agencies' issues and respond to our legal obligations in a timely manner," Mr. Johnson wrote in a preface to the document.

The lengthy document, called an Advance Notice of Proposed Rulemaking, summarized the EPA's work so far and contained letters by other agencies expressing objections and questions. Objections were raised by the departments of Agriculture, Commerce, Transportation and Energy as well as White House offices including the Council on Environmental Quality.

Critics said the administration was refusing to take action.

"The Bush administration decision today to effectively reject regulation of global warming pollution under the Clean Air Act creates a clear and present danger to the American people," said Sen. Barbara Boxer, D-Calif.