The Environmental Protection Agency yesterday began to roll back tough fuel-economy standards for cars, a step that will make it more difficult to clean up air pollution in New Jersey, including emissions contributing to climate change.

EPA Administrator Scott Pruitt faulted the Obama administration for setting the standards too high for cars and light trucks, an argument advanced by automakers as too costly to achieve. “The Obama administration’s determination was wrong,’’ Pruitt said in a press release.

In the same release, Pruitt indicated the agency may eliminate a waiver that allows California to impose stricter standards for vehicle-tailpipe emissions than the federal government. New Jersey is one of 12 states committed to follow those more stringent standards, deemed crucial to complying with a law to dramatically curb greenhouse-gas emissions.

“The EPA will set a national standard for greenhouse-gas emissions that allows auto manufacturers to make cars that people both want and can afford,’’ Pruitt said. “It is in America’s best interest to have a national standard, and we look forward to partnering with all states, including California, as we work to finalize that standard.’’

Fuel economy of the future

The fuel-economy standards were projected to result in average fleet-wide consumer fuel economy of 54.5 miles per gallons by model year 2025 — much higher than the current fleet average of 36 mpg.

“The American public overwhelmingly supports strong vehicles standards because they cut the cost of driving, reduce air pollution, and combat climate change,’’ said Luke Tonachel, director of the Natural Resources Defense Council’s clean vehicles and fuels project. “Backing off now is irresponsible and unwarranted.’’

“It’s a huge environmental rollback,’’ agreed Doug O’Malley, director of Environment New Jersey. “This is environmental war.’’

In New Jersey, the transportation sector is the biggest source of greenhouse-gas emissions, and also a big contributor to the ground-level ozone or smog that blankets the state in summertime. The demise of the fuel-economy rule may force the state to clamp down further on stationary sources of pollution like factories, refineries, and other businesses, according to some.

“We’ve ratcheted things back more than other states have and yet we still have trouble meeting federal clean air standards,’’ said Dennis Toft, chair of the environmental department at Chiesa, Shahinian & Giantomasi. Upwind states that have not adopted as strong pollution controls as New Jersey are to blame, he said.

“Clean car standards protect all Americans from unnecessarily high fuel costs and from pollution that is dangerous to public health,’’ said Daniel Sosland, president of the Acadia Center, an advocacy group for a clean-energy future. “Rolling back these standards will damage the country’s economy and its competitive position, contrary to erroneous assertions by EPA.’’

Lengthy litigation?

It also is likely to trigger lengthy litigation, particularly if California’s clean-car waiver is repealed. California has threatened to sue if it is blocked from adopting more stringent standards than the EPA.

The environmental agency heads of 10 states, including Catherine McCabe, the acting commissioner of the New Jersey Department of Environmental Protection, and the District of Columbia jointly wrote a letter yesterday to the EPA expressing deep concern with Pruitt’s decision.

“Any weakening of the standards would increase pollution from cars and light trucks, with adverse public health and environmental impacts,’’ the letter said. “States and our nation need to continue to increase efforts to reduce air pollutant emissions, and cars and light trucks are among the largest sources of these contaminants.’’

The letter from the commissioners also urged Pruitt to retain the waiver for California to impose more stringent tailpipe emissions. The standard is expected to lead to automakers offering zero-emission vehicles that do not contribute to greenhouse-gas emissions.

The EPA action is the latest move regarded by environmentalists as a concerted bid to relax laws governing public health and the environment. Last June, the agency put a hold on federal regulations governing smog, the state’s most pervasive air pollutant. It is formed from pollution from cars, trucks, factories, businesses, and other sources.