The battle lines aren’t officially drawn yet, but the fight is already intense.

Next week, the Obama administration will propose new rules for curtailing greenhouse gas emissions from existing power plants, the source of about 40 percent of U.S. carbon pollution. The proposal from the Environmental Protection Agency under Section 111(d) of the Clean Air Act will have to go through extensive public vetting, and will almost certainly face legal challenges, but already this week opponents and proponents were clobbering each other with studies and press releases.

The White House made extraordinary outreach efforts on the rules over the past year, hoping to build momentum for acceptance, and the EPA has insisted that whatever action it takes, states will have wide flexibility in devising their plans to trim carbon emissions. And some power companies have signaled an open mind on the question.

But regulations with such potentially profound impact – the “Crown Jewel” of the president’s climate strategy, according to White House counselor John Podesta – remain a hot-button issue with many – and especially with the powerful U.S. Chamber of Commerce.

The Chamber on Wednesday released a study that it said showed “potential” regulations would mean “Americans will pay significantly more for electricity, see slower economic growth and fewer jobs, and have less disposable income, while a slight reduction in carbon emissions will be overwhelmed by global increases.”

The Chamber said it used a plan devised by the Natural Resources Defense Council – widely expected to guide the EPA in its rulemaking – as the basis for its study, which relied on modeling and analysis from the consultant IHS. In a press release, however, the NRDC said the Chamber study was just “the latest in a long series of ‘sky-is-falling’ warnings of job losses and economic costs that are a big lie – part of the polluting industry’s disinformation campaign to preserve its profits by thwarting efforts to protect public health and curb climate change.”

The NRDC was set to release its own economic impact study this week, but in an earlier analysis the group had said that depending on how aggressively emissions are cut, its proposal “would stimulate investments of $52 billion to $121 billion in energy efficiency and renewables between now and 2020, boosting local and state economies.”

The advocacy group Public Citizen jumped into the fray this week, as well, noting that some “regulated electric utilities (American Electric Power, Dominion Resources, Xcel and more) are saying relatively benign, if not supportive things about the June 2 power rule,” but “the Chamber, increasingly staffed by former GOP political operatives, is attacking the EPA regulations not from a business perspective, but from a purely political one.”

Under the NRDC proposal, unveiled in 2012, the EPA would set overall emissions rates, first for 2020 and then lower for 2025, specific to each state based on a baseline determination of coal and gas generation. The proposal outlines a range of possible emissions levels the EPA could set – a key unknown at this point – and it would then be up to the states to devise mechanisms, including carbon trading schemes, to meet the standard.

In addition to spurring cleaner energy generation, the NRDC sees energy efficiency as an “innovative” feature of the plan, wherein “state-regulated energy efficiency programs could earn credits for avoided pollution resulting from reduced electricity consumption.” This resulting reduced consumption would be a factor in holding down costs for consumers, the NRDC’s David Doniger said in an interview on Wednesday.

While the fight over the upcoming rule’s economic impact raged, renewable energy developers, who have been fighting to maintain policy incentives like the production tax credit and the renewable portfolio standards, were looking to take advantage of any new EPA regulations: The American Wind Energy Association this week put out a white paper that promoted wind power – which has grown to account for more than 4 percent of U.S. electricity generation – as “one of the biggest, fastest, cheapest ways states can comply with the forthcoming EPA rule limiting carbon pollution from existing power plants.”