Environmental Protection Agency Administrator Scott Pruitt signed a proposed rule on Tuesday that would repeal the centerpiece of former President Barack Obama's climate change agenda, the Clean Power Plan.

"The Obama administration pushed the bounds of their authority so far with the CPP that the Supreme Court issued a historic stay of the rule, preventing its devastating effects to be imposed on the American people while the rule is being challenged in court," Pruitt said in signing the rule. "We are committed to righting the wrongs of the Obama administration by cleaning the regulatory slate. Any replacement rule will be done carefully, properly, and with humility, by listening to all those affected by the rule."

The plan, which restricts greenhouse gas emissions from coal-fired power plants, was the subject of an earlier executive order signed by President Trump directing Pruitt to take Tuesday's action. The rule marks a key milestone in the president meeting one of his major campaign promises.

Tuesday's action is a proposed rule, which means it must go through a public comment period before it can be finalized and take effect. Upon publication in the Federal Register, the public, industry and all other stakeholders will have 60 days to file comments with the agency, according to Tuesday's notice of proposed rulemaking. That means the comment period will go into December and a final repeal rule likely will not come until next year.

The EPA said Tuesday's proposed rule includes a preamble that "lays out the proposed legal interpretation, policy implications and a summary of the cost-benefits analysis of the proposed repeal." The rule also includes a "Regulatory Impact Analysis," which includes an "in-depth cost-benefit technical analysis."

Comments from the industry, environmentalists, consumers and other stakeholders will hone in on those justifications in submitting comments that support the repeal or lash back against it. Several Democratic state attorneys general and environmental groups have said they will sue if Pruitt repeals the rule.

The agency's cost-benefit analysis focuses on the avoided costs of not having to comply with the Clean Power Plan. "The Trump administration estimates the proposed repeal could provide up to $33 billion in avoided compliance costs in 2030," the agency said in a summary of the rule.

The EPA added that the Obama administration's "estimates and analysis" on the "cost and benefits" of implementing the rule through pollution reduction and public health savings "was, in multiple areas, highly uncertain and/or controversial." Specific areas that the EPA criticized included "domestic versus global climate benefits" in which the Obama administration "compared U.S. costs to an estimate of supposed global benefits, and failed to follow well-established economic procedures in estimating those benefits."

Other areas of the Obama-era analysis include arguments over the "co-benefits" of the greenhouse gas rules in reducing conventional pollutants such as sulfur dioxide and particulate matter from older fossil fuel power plants. The Pruitt EPA argues that the co-benefits argument helped the Obama adminsitration hide the true cost of the Clean Power Plan "by claiming benefits from reducing pollutants that had nothing to do with the rule's stated purpose."

Pruitt also goes after the Obama EPA's "energy cost and savings accounting," which equated energy efficiency savings under the rule as an avoided cost, "resulting in a cost estimate being considerably lower than it would have been if they used the appropriate practice of considering these effects as benefits, rather than subtracting them from costs."

Pruitt's proposed repeal will be followed by another proposed rulemaking on a regulation that would replace the Clean Power Plan. "Forthcoming is an Advanced Notice of Proposed Rulemaking that will be reflective of a thoughtful and responsible approach to regulatory action grounded within the authority provided by the statute," the EPA said.

The Clean Power Plan has been on ice since February 2016, when the Supreme Court blocked it as it worked its way through the courts. The D.C. Circuit Court of Appeals heard oral arguments from more than two dozen states and over 100 industry groups challenging the Obama-era rules in September 2016, but has not ruled on the case. The appeals court agreed with Pruitt to hold its decision on the plan in abeyance while EPA works out the repeal process. The court's deadline for Pruitt to act was Oct. 6.

Pruitt said Monday that the withdrawal of the plan would come Tuesday. Many climate scientists blame greenhouse gas emissions from burning fossil fuels for driving man-made climate change.

The states had argued in the D.C. Circuit Court that the EPA overstepped the bounds of the Clean Air Act, which is where the EPA derives its authority to regulate power plants. Since the climate rules go far beyond regulating power plants, and turn instead to regulating statewide greenhouse gas emissions, the states say the Clean Power Plan is illegal, which is Pruitt's thinking. Pruitt, as Oklahoma's former attorney general, was one of the 27 attorneys general challenging the rule in court.

Tuesday's signed proposal said the Obama administration's plan was based on a "novel and expansive view" of EPA's authority under the Clean Air Act. The agency said the Trump administration proposes to determine that view is "inconsistent" with the law.

"The [Clean Power Plan] ignored states' concerns and eroded longstanding and important partnerships that are a necessary part of achieving positive environmental outcomes," Pruitt said. "We can now assess whether further regulatory action is warranted; and, if so, what is the most appropriate path forward, consistent with the Clean Air Act and principles of cooperative federalism."