Environmental groups and some members of the business community are trying to put political pressure on U.S. Sen. Susan Collins to publicly support the Obama administration’s proposal to regulate carbon dioxide emissions from power plants.

About a dozen people gathered Friday morning in Lobsterman’s Park near Collins’ Portland office to urge the Maine Republican to back plans by the U.S. Environmental Protection Agency to reduce carbon dioxide emissions from power plants by 30 percent by 2030. The EPA is still gathering public comment on the proposal, but the issue is likely to spark debate in Congress from both backers and detractors in the run-up to the November elections.

“As she goes back to Washington, we want her to know that Maine people and businesses support action on climate (change), that we have her back and we urge her to stand up and support the EPA’s clean power plan,” said Dylan Voorhees of the Natural Resources Council of Maine.

Thoseat the news conference – including a former lobsterman and a representative of the wind energy industry – then went to Collins’ office to present a letter signed by more than 400 Maine business owners urging support for the EPA rules. The letter was also addressed to Sen. Angus King, I-Maine, who has expressed support for the regulations.

Collins is the only member of Maine’s four-member congressional delegation who has not explicitly backed the EPA rules, although she has defended the EPA’s ability to regulate greenhouse gases. Her spokesman, Kevin Kelly, said Friday that Collins “has always supported reducing harmful emissions from coal-fired power plants, which threaten public health and the environment,” but that climate change requires reducing greenhouse gas pollution worldwide.

“She is carefully reviewing EPA’s wide-ranging and complex proposal to reduce carbon emissions from existing fossil-fueled power plants,” Kelly said in a statement. “The public comment process will provide states, stakeholders, and the public with the opportunity to evaluate and comment on the new proposal, including its impact on public health, the affordability of electricity rates, and the effect on the economy.”

The EPA proposal on carbon dioxide is the Obama administration’s most aggressive initiative to reduce emissions of greenhouse gases linked to climate change. Each state was assigned a different reduction target based on a host of factors, including the state’s reliance on coal-burning power plants, which are among the largest emitters of carbon dioxide, as well as mercury and other pollutants.

Maine would be expected to reduce carbon dioxide emissions by 13.5 percent by 2030. Although the details have yet to be worked out, Maine and eight other Northeastern states appear well-positioned to comply with the federal rules because fossil fuel-burning power plants in the region have been operating for five years under a cap-and-trade program to reduce carbon dioxide emissions.

The EPA proposal is highly controversial elsewhere, however. Political and business leaders in coal-mining or coal-dependent states are working overtime to squelch the proposed rules, which they predict will drive up electricity costs and cause massive job losses in the mining sector.

Collins, a moderate Republican, has bucked her party on at least two occasions by voting against proposals to block the EPA from regulating greenhouse gas emissions. And she is regarded by some national environmental groups as one of the friendlier Senate Republicans on key issues, even picking up an endorsement from the League of Conservation Voters Action Fund.

Her opponent in the November election, Democrat Shenna Bellows, has suggested that Collins’ unclear stance on the EPA rules is part of a broader trend of the Republican hedging on major issues. She has called on Collins to publicly distance herself from an effort by Senate Minority Leader Mitch McConnell, R-Ky., to scuttle the EPA proposal.

The proposed regulations on carbon dioxide emissions are EPA rules, not legislation. But the issue is likely to be debated within the halls of the U.S. Capitol, nonetheless.

A group of conservative Republicans launched an investigation into alleged collusion between the EPA and the Natural Resources Defense Council when crafting the carbon dioxide rules. The group includes the chairman of the House Oversight and Government Reform Committee, Rep. Darrell Issa of California, and Sen. David Vitter of Louisiana, the top Republican on the Senate Environment and Public Works Committee.

Taryn Hallweaver, campaigns director with Environment Maine, said during Friday’s news conference that “we need leaders to step up and act” in the face of intense lobbying from the coal industry and electric utilities against the EPA rules. She said more than 39,000 Maine residents have sent letters, emails or postcards in support of the Obama plan.