The Federal Register publication on Oct. 23 of the first-ever federal limits on carbon emissions from power plants started a promised battle between the Obama administration and opponents of the rule, both in federal courts and on Capitol Hill.

A top Environmental Protection Agency official, Janet McCabe, in a call with reporters on Oct. 22 resisted any notion that the landmark rule is vulnerable to efforts by opponents to kill it, a stance backed by environmental advocates.

EPA Administrator Gina McCarthy, in a blog post at the end of last week, added that the rule is “grounded firmly in science and the law.”

Yet the rush to stop the rule, known as the Clean Power Plan, was immediate.

Critics made good on their vows to fight back in the halls of Congress and in the U.S. Court of Appeals for the District of Columbia with suits by states and industry that could end up before the Supreme Court.

It’s a fight that will determine whether President Barack Obama’s signature action to address climate change, which takes on the biggest source of U.S. greenhouse gas emissions, will remain on the books after he leaves the White House.

The rule aims by 2030 to drive down power plant carbon emissions 32 percent below 2005 levels. It is a key part of Obama’s pledge to reduce total U.S. emissions 26 percent to 28 percent by 2025, one he hopes will persuade other nations to sign a global, if nonbinding, climate agreement in Paris this December.

The publication of the rule came more than two months after the EPA finalized its text on Aug. 3, a delay it said was not extraordinary, though critics said the rule was held up to ensure any court action against it did not happen before the Paris conference.

McCabe said states have begun engaging with the EPA on the rule as they prepare to write compliance plans, with initial drafts due by next September and final plans due by 2018.

State Resistance

A handful of states have threatened to resist compliance, however, which would lead to the imposition of an EPA plan. Oklahoma Gov. Mary Fallin, a Republican, has issued an executive order prohibiting state agencies from drafting one.

Senate Majority Leader Mitch McConnell, R-Ky., has urged governors to resist submitting compliance plans, based on his argument that the rule will be overturned in federal courts.

McConnell wasn’t looking solely to the courts as the rule became operative on Oct. 23, however. He said he would join with three pro-coal colleagues to introduce two disapproval resolutions under the Congressional Review Act to cancel the key parts of the rule that affect new and existing power plants. The 1996 law allows Congress to block recent agency rules by passing a joint resolution of disapproval, which cannot be filibustered. The procedure has only worked once in the past, and it won’t this time because the president can veto the disapproval resolution.

Joining McConnell are West Virginia Sens. Shelley Moore Capito, a Republican, and Joe Manchin III, a Democrat, as well as Heidi Heitkamp of North Dakota, also a Democrat.

McConnell said he would schedule floor votes for the resolutions.

“I have vowed to do all I can to fight back against this Administration on behalf of the thousands of Kentucky coal miners and their families, and this CRA is another tool in that battle,” McConnell said in a statement. “The CRAs that we will file will allow Congress the ability to fight these anti-coal regulations.”

‘Economic Disaster’

Over in the House, another Kentucky Republican, Edward Whitfield, said he will introduce two similar resolutions on Monday.

“Now we’ve got EPA’s cap and trade rules, a blueprint for economic disaster, right there in black and white in the Federal Register,” he said in a statement.

At the same time the Kentucky duo was readying the resolutions, industry and trade groups, and a coalition of 24 states, rushed at the end of the week to launch a two-pronged attack on the rule at the U.S. Court of Appeals for the District of Columbia.

They were to petition the court for a stay of the rule, while their suits seeking to have the rule struck down as illegal under the Clean Air Act are heard.

West Virginia Attorney General Patrick Morrisey, who announced the states’ lawsuit, said the rule “unlawfully expands the federal government’s regulatory power over electricity production and consumption in nearly every state.”

He and officials of 14 other states previously sought to have the rule declared illegal and win a stay until suits were heard, but that suit and the stay petition were rejected by the appeals court as premature.

The U.S. Chamber of Commerce on Oct. 23 also filed a suit and a petition for a stay with the D.C. court on behalf of itself and 15 other trade groups.

Ohio-based Murray Energy Corp., the nation’s largest miner of underground coal, which also sought to stop the rule during its proposal phase, filed suits challenging the rules for both existing and new plants.

“We have no choice but to challenge the Obama administration’s illegal actions in court, and we will prevail,” asserted Robert E. Murray, the company’s president.

Also throwing its suit into the mix was the National Mining Association. It’s president, Hal Quinn, said the court should quickly stay the rule, even though it does not require formal action by states to meet their own carbon targets until 2022.

“The immediacy of substantial harm from this power plant rule is plain from EPA’s own data that show it will cause more than 200 coal-fired power plants to close before courts have time to decide the legality of the rule,” Quinn said in a statement.

Yet environmental groups and another group of at least 15 states, plus three cities, said they were preparing to intervene in the federal court proceedings to help the EPA defend the rule.

Michael J. Myers, an assistant attorney general for New York state, told reporters that opponents likely won’t be able to win a stay from the court, because the EPA in the final rule gave states and industry more time to comply.

“At the end of the day, be it in the near term or the long term, these challenges are likely to fail and this very important rule is likely to be upheld by the courts,” he said.