More than two dozen states filed lawsuits Friday seeking to block the Obama administration’s signature climate-change regulation in a wave of opposition that coincided with new calls from scientists and even former Republican administration officials for deeper cuts in carbon pollution for the sake of the planet.

The flurry of litigation was triggered by the official promulgation of the White House’s Clean Power Plan, an ambitious and controversial regulation that seeks to dramatically reduce heat-trapping emissions from electric utilities, mostly by cutting reliance on coal.

Opponents of the plan waited for Friday’s publication of the rule in the Federal Register to file lawsuits accusing the administration of unlawfully using the federal Clean Air Act to force states to curb emissions of greenhouse gases blamed for global warming.

“The Clean Power Plan is one of the most far-reaching energy regulations in this nation’s history,” said Patrick Morrisey, attorney general of West Virginia, which joined 23 other states in a lawsuit filed in federal court in Washington. Two other states, Oklahoma and North Dakota, filed suits separately.

Noting that coal-burning was the regulation’s primary target, Morrisey said his state was “proud to be leading the charge against this administration’s blatant and unprecedented attack on coal.”

Despite the legal challenges and rhetoric, some states that are parties to the lawsuit are simultaneously considering developing plans for complying with the rule. The Clean Power Plan offers extensive incentives for states to come up with their own strategies for meeting the carbon-cutting goals set by the Environmental Protection Agency. EPA officials and some outside experts say most states could meet the targets with relatively little pain by establishing regional carbon-trading plans that allow bigger polluters to buy pollution-cutting credits from utilities that make electricity from natural gas or renewables such as wind and solar power.

EPA Administrator Gina McCarthy defended the regulation Friday as having “strong scientific and legal foundations,” and she predicted the agency would prevail in court.

“Because greenhouse gas emissions threaten public health and welfare, EPA is using its authority under the Clean Air Act to regulate sources­ of these pollutants, including in the power sector,” McCarthy wrote in a blog published on the agency’s Web site.

The Clean Power Plan, adopted in August, is a cornerstone of the administration’s plan to reduce U.S. carbon emissions by up to 28 percent by 2030, compared with 2005 levels.

Other states have voiced strong support for the carbon-cutting plan, which, if implemented, is expected to also lead to improved air quality in many of the nation’s cities. The EPA’s rule was defended Friday by a diverse group that included state regulators, environmentalists, climate scientists and even a pair of former EPA administrators from Republican administrations.

“The country needs to reduce [carbon dioxide] from existing power plants which generate 40 percent of America’s CO2,” said a joint statement by William K. Reilly, the EPA chief during the George H.W. Bush administration, and William D. Ruckelshaus, who led the agency in the administrations of Richard M. Nixon and Ronald Reagan. “The rule is needed, and we hope the courts will recognize that it is on the right side of history.”