The Environmental Protection Agency will seek public comment on the effects of greenhouse-gas emissions from mobile and stationary sources, such as automobiles and electrical plants, a controversial decision that could delay regulation until as late as 2009.

In a letter to Congressional leaders, EPA Administrator Stephen Johnson says the agency will propose rules “later this spring” that will begin what could be a long period of public comment. The letter comes in response to a U.S. Supreme Court ruling last year calling for the EPA to reconsider its 2003 decision to not regulate greenhouse-gas emissions for automobiles.

Johnson’s decision arrives as environmentalists seek to challenge the EPA’s ruling that states, such as California, cannot regulate greenhouse-gas emissions from vehicles under the Clean Air Act. The EPA decided last year after the passage of new corporate average fuel economy standards that it would be the sole regulator of emissions, such as carbon dioxide.

Johnson’s decision seems to delay that role and infuriates Democrats, who view it as a ploy to put off emissions regulation until President Bush leaves office in 2009.

“I recognize that the current Clean Air Act may not be the best mechanism for regulating greenhouse gases,” says U.S. Rep. John Dingell (D-MI) in response to Johnson’s letter. “But it is puzzling and disappointing that the Bush Admin. hasn’t offered an alternative or joined the effort to design and enact comprehensive climate-change legislation.

“In upcoming hearings, we will be examining the strengths and shortcomings of regulating greenhouse-gas emissions through the Clean Air Act.”

Sen. Barbara Boxer (D-CA) called Johnson’s decision “more foot-dragging.” But the Competitive Enterprise Institute, a conservative Washington lobbyist, endorsed the move.

“Johnson sets forth several complex issues that the EPA must resolve before finalizing its response to the (Supreme) Court,” says Marlo Lewis, a senior fellow at CEI.

“These include the relationship between recent statutory changes in the EPA’s responsibilities regarding fuel economy and renewable-fuel standards and the new auto emission standards that might result from the court case.”

Had Johnson not called for public comment, his agency probably would have begun rulemaking for emissions regulations this year on cars and trucks, exclusively. Meanwhile, California and at least a dozen other states are prepared today to regulate vehicles emissions using the Clean Air Act.