A handful of states filed a lawsuit Tuesday against the Trump administration for not finalizing energy-efficiency regulations issued by the Obama administration’s Energy Department. Rick Perry, energy secretary, is seen here at the opening ceremony of an international clean energy conference held last week in Beijing. (Ng Han Guan/AP)

Eleven states, led by California and New York, have sued the Trump administration for failing to finalize energy-efficiency regulations for portable air conditioners, walk-in coolers and other products.

The lawsuit, filed on Tuesday, represents the latest front in an escalating legal battle over the remaining pieces of Obama’s climate change legacy — led by a coalition of blue states, which are also fighting attempts to roll back Obama’s Clean Power Plan.

The pro-climate states have already made headway. Earlier, the Energy Department announced it would move ahead on energy-efficiency standards for ceiling fans, after a prior lawsuit by New York Attorney General Eric Schneiderman and his colleagues. The agency said that the regulation would take effect in September.

The current lawsuit involves the final five in a large batch of rules issued by the Obama administration’s Energy Department, which were left in a curious state of limbo after Trump’s inauguration.

The standards were finalized shortly before Trump’s inauguration, but subjected to a mandatory 45 day “error correction” review, focused on catching typographical errors and other minor problems.

But the Trump administration did not, at the end of that review period, send the regulations on for formal publication in the Federal Register.

The case was filed by attorneys general from the states of California, New York, Maine, Connecticut, Illinois, Vermont, Oregon, Washington, Maryland, Massachusetts, Pennsylvania, and the city of New York. Three environmental and public interest organizations, the Sierra Club, Natural Resources Defense Council and Consumer Federation of America, also filed suit Tuesday on the same topic.

The regulations cover air compressors, commercial boilers, portable air conditioners, uninterruptible power supplies and walk-in freezers.

The rules require manufacturers to improve the energy efficiency of their products over time, so as to consume less energy for the same level of performance.

The Obama administration had depicted such regulations as a key piece in its push to reduce the United States’ greenhouse gas emissions in line with the Paris climate agreement — from which the Trump administration has said it will withdraw.

Energy-efficiency regulations reduce greenhouse gas emissions from electricity and also save consumers money. In this case, according to the states, the standards could save $ 24 billion over a period of 30 years.

“If they don’t take effect, then consumers are the ones who really lose,” said Lauren Urbanek, a senior energy policy advocate for the Natural Resources Defense Council, one of the groups suing over the incomplete regulations.

It isn’t clear why the regulations are being held up, but four of them were apparently put on hold very early in the Trump administration when the new government put in place a regulatory freeze.

Since then, the Trump administration has also put in place a regulatory policy that requires the dismantling of two regulations for every new one issued.

A spokesman for the Energy Department said that the agency “does not comment on pending litigation.”

One of the near-final regulations, regarding commercial boilers, also has run into opposition from industry.