Democrats and environmental groups generally rejected Bush's "Clean Skies" initiative as a step backward that would delay clean-up measures already under way.
The President proposes mandatory national limits on three types of pollution from power plants, but would drop other regulations that apply to power plants and delay their enforcement dates.
Reductions required by 2018 would cut nitrogen oxides, which cause smog, by 67 percent; sulfur dioxide, which produces soot and acid rain, by 73 percent; and mercury, which taints water supplies and fish, by 69 percent.
Bush would allow another pollutant, carbon dioxide, which causes global warming, to grow, but at a rate 4.5 percent slower than projected.
The power plant pollution caps are looser and take effect later than a version the administration presented to the utility industry last fall.
The greenhouse gas goal for 2012, consisting mainly of carbon dioxide, is 40 percent higher than President Clinton's 1997 goal and 30 percent higher than the goal President Bush's father set in 1992.
"It's really a rollback of the Clean Air Act masquerading as a step forward," said Frank O'Donnell, executive director of the Clean Air Trust, a Washington environmental group. "It's very much like what the industry has called for: eliminating current requirements and replacing them with a less restrictive system."
Bush, business and energy leaders laud the plan for freeing power plants - among the nation's biggest polluters - from intricate regulations. Instead, they would be given pollution limits for each plant. Those that failed to meet the limits would be able to buy pollution credits from plants that exceeded them.
"Instead of the government telling utilities where and how to cut pollution, we will tell them when and how much to cut," Bush said, speaking to the Silver Spring, Md., office of the National Oceanic and Atmospheric Administration. "We will give them a firm deadline and let them find the most innovative ways to meet it."
Congress still must approve Bush's plan.
"It's a very reasoned plan to get to a practical result," said Bill Kovacs, environment and energy vice president for the U.S. Chamber of Commerce, a business lobby in Washington. "It gives you a lot of incentives [to clean up] faster."
Kovacs and Bush predicted an active market in pollution credits and noted that a similar "cap and trade" system, introduced in 1990 to reduce acid rain, had proven successful and cheap.
"Cap and trade is a wonderful engine," said Joseph Goffman, senior lawyer for Environmental Defense, a moderate New York environmental group, but he criticized Bush's cleanup goals as too modest. "What the President essentially offered is a Ferrari for cleaning up the air, but he's only willing to drive it at 15 m.p.h."
"The administration may be able to fool the American people that they're doing something, but they can't fool the atmosphere," said Dan Becker, a spokesman for the Sierra Club.
Among the critics of the plan was Bush's 2000 campaign opponent, former Vice President Al Gore, who has been sounding the alarm on global warming for more than a decade.
"The United States can and should lead the world to a clean technology future," he said in a statement. "Unfortunately this plan abdicates the responsibility instead of accepting it."
House Minority Leader Richard A. Gephardt (D., Mo.) said both of Bush's proposals "fall short of the mark."
"Unfortunately, the administration continues to press for a 19th century energy policy that simply rewards oil, gas and utility special interests," Gephardt said.
Sen. John Kerry (D., Mass.) called Bush's plan "all procrastination and no progress. It may well lead to more pollution, not less."
On global warming, Bush's plan is entirely voluntary. It is based on tax credits of $4.6 billion over five years. The credits would reward use of solar energy, fuel cells, renewable energy, and hybrid gas-electric cars.
In addition, companies could submit tallies of their greenhouse gas pollution cuts, for which they would be credited in the event of future regulation.
Environmental groups said voluntary programs were not enough.
"You need mandatory caps like you have in the Kyoto Protocol to bring emissions down," said Jennifer Morgan, climate change program director for the World Wildlife Fund.
The Kyoto Protocol, which Bush rejected last year as unfair and economically stifling to the United States, set pollution limits that signatories pledged to meet. The U.S. limit would have been 40 percent below Bush's current goal.
Jim Connaughton, chairman of the president's Council on Environmental Quality, said if this voluntary program did not work, the administration would look at other voluntary programs.
Seth Borenstein's e-mail address is firstname.lastname@example.org.