WASHINGTON —The nation’s largest cities are stepping up in defense of President Obama’s plan to slow climate change by reducing greenhouse gas emissions – in many cases taking the opposite legal position from their state governments.

The U.S. Conference of Mayors and the National League of Cities on Tuesday filed motions in support of the Clean Power Plan with the U.S. Court of Appeals in Washington.

The groups are opposing lawsuits filed in October against the Environmental Protection Agency by more than two dozen mostly Republican-led states and allied industry groups reliant on fossil fuels. Led by Texas and West Virginia, the conservative states deride the plan as an “unlawful power grab” that will kill coal-mining jobs and drive up electricity costs.

The carbon-cutting rules are essential to the United States meeting emissions-reduction targets agreed to in a global climate agreement signed in Paris earlier this month. The Obama administration and environmental groups also say the plan will spur new clean-energy jobs.

The U.S. Conference of Mayors is a non-partisan organization representing more than 1,200 cities with populations larger than 30,000. The National League of Cities represents more than 19,000 municipalities that are home to a combined 218 million Americans.

The dueling legal actions for and against the climate plan are in several instances pitting city leaders against governors and attorneys general of their own states.

In addition to the municipal advocacy groups, the cities of Houston, Los Angeles, Minneapolis, San Francisco and West Palm Beach, Florida, have joined the list of local governments supporting the president’s plan. New York City, Chicago, South Miami and other large cities filed motions in support last month, along with several Democratic-led states such as California and New York.

In a motion filed Tuesday, the local government coalition said their cities are already suffering from the impacts of climate change.

Houston, home to more than 2 million people, is contending with increasingly severe and frequent heat waves, droughts, storms and floods. South Florida cities such as West Palm Beach and Coral Gables are seeing rising seas erode and invade the limestone bedrock on which they are built and rely on for drinking water. Such Mid-Atlantic cities as Baltimore and Jersey City, New Jersey, are put at risk by rising seas and stronger storms, according to the court filings.

The mayors of Houston, West Palm Beach, Florida and Jersey City, New Jersey, are all Democrats in states with Republican governors that oppose the EPA rule.

States opposing the new rule have said they mandate an unrealistic time frame for drastic emissions reductions and would require the use of costly and unproven technologies.