The Capitol Dome is seen behind the Capitol Power Plant in Washington, D.C., on June 24, 2013. (Carolyn Kaster/AP)

When President Obama announces new rules Monday governing carbon emissions from coal plants, some of the loudest cries of opposition are likely to come from members of his party.

The regulations, aimed at combating a rapidly changing climate by implementing state-by-state limits on greenhouse-gas emissions, will shine a spotlight on a growing division within the Democratic Party: On one side are major donors, who take a particular interest in environmental causes and are becoming increasingly important to the party. On the other are candidates from energy-producing states — where regulations on coal-fired power plants could have the most detrimental effects — whose fates will decide control of the Senate.

Those candidates — most notably Sens. Mary Landrieu (La.), Mark Pryor (Ark.), Mark Begich (Alaska), Kay Hagan (N.C.) and, to a lesser extent, Mark Udall (Colo.) — are on the front lines of the battle for the Senate. Their Republican opponents will almost certainly use Monday’s announcement to attack them.

“Every American’s electricity bills will get more expensive, and we will force-feed those electric bills back to every Democratic candidate,” said Brad Todd, a Republican strategist working for Hagan’s and Pryor’s opponents. “When any politician gets caught making life more expensive for the middle class, he or she is in harm’s way.”

Landrieu has been the most vocal Democrat resisting the ­administration’s environmental proposals. In May, Landrieu introduced a measure with Sen. John Hoeven (R-N.D.) that would have immediately authorized construction of the Keystone XL pipeline, a bill co-sponsored by Pryor, Begich and Sen. John Walsh (Mont.), another energy-state Democrat facing a tough fight this year.

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As chairman of the Senate Energy and Commerce Committee, Landrieu has used campaign advertisements to tout her influence as a boon to Louisiana’s oil and gas industries. Last week, she guided Energy Secretary Ernest Moniz on a tour of oil and gas hubs along the Gulf Coast.

Kentucky Secretary of State Alison Lundergan Grimes (D), who faces a tight contest against Senate Minority Leader Mitch McConnell (R) in the heart of coal country, has said she would use the Senate seat to try to curb the “most restrictive” regulations on coal-fired power plants.

“Coal keeps the lights on in Kentucky — plain and simple — and I will not stand idle as overreaching regulation adversely impacts jobs and middle-class families,” Grimes said in September. After the EPA proposed limiting carbon output, Grimes said the Obama administration “has taken direct aim at Kentucky jobs.”

Democratic strategists say their energy-state candidates have to make clear their opposition to the forthcoming EPA rule, lest it hurt their chances.

“If I were running, I would get the governor to sue and try to tie it up in the courts,” said Jim Cauley, a Kentucky-based Democratic strategist who managed Obama’s first Senate campaign. “Coal has just become the cultural litmus test as to whose side you are on.”

That puts big Democratic donors for whom environmentalism and climate change are leading causes, led by California investor and billionaire Tom Steyer, in the awkward position of supporting candidates who don’t take the same view. Steyer has said he will spend up to $50 million of his own money and an additional $50 million through his NextGen Climate Action PAC on Democratic candidates in the 2014 midterm elections.

Steyer has not directly spent money on behalf of Landrieu, Pryor, Hagan or Grimes. But his money will at least indirectly help energy-state Democrats: Steyer has contributed $5 million to the Senate Majority PAC, which has spent heavily in Louisiana, North Carolina and Arkansas. A Senate Majority PAC spokesman declined to say whether Steyer’s money came with stipulations on where it could be spent, but regardless every dollar spent elsewhere frees another donor’s dollar for Landrieu, Pryor, Hagan or Grimes.

“People do recognize that ’14 is a pivot year for climate, because of the fact that on an everyday basis people are feeling a direct, immediate pocketbook impact on their daily lives,” said Chris Lehane, a Democratic strategist who advises Steyer. Races that Steyer and others are investing in are contests critical to maintaining a Senate majority.

“You’ve got to win Iowa, you’ve got to win New Hampshire, you’ve got to keep Colorado” to keep the majority, Lehane said. In each state, Steyer-funded ads will point to immediate threats posed by climate change, whether through droughts, flooding, fracking or public health. “As much as I love polar bears and I love butterflies, we’re not going to be talking about them in these campaigns.”

The balance between acting on environmental issues that are high priorities for Obama and the left and creating jobs in energy-producing states represented by Democrats has come up several times in recent years. Energy-state Democrats have pushed the administration to approve the Keystone XL pipeline and open new lands for oil and gas exploration. Strategists close to those big donors say they are less concerned with Landrieu’s position on oil drilling or Pryor’s support for Keystone than the larger goal of salvaging the Democratic majority in the Senate.

“This race is not about fracking, it’s about control of the United States Senate and a number of public policies that will be affected by that,” said David Kenney, a Colorado Democratic strategist who bundled more than $1 million for Obama in the 2012 election cycle and organizes fundraisers for senators visiting Denver. “I haven’t heard anybody say I won’t vote for this person or that person over fracking. Every conversation I’ve been in is, we cannot lose the United States Senate.”

Instead, environmental groups such as the League of Conservation Voters place a higher priority on EPA regulations, where they say the battle over climate change will be won or lost, than on Keystone, which would have a relatively small impact. LCV said it will spend money to defend Hagan and Begich even though they support the pipeline because the pair have defended previous EPA rules.

“This is the biggest step we’ve ever taken for the biggest challenge we’ve ever faced,” said LCV President Gene Karpinsky. “There are some incumbent senators who are consistently on record against us, and so be it. But we will be standing with those senators who stand for clean air and public health.”

The Democratic debate over energy policy and climate change is further complicated by governors, particularly in Western states, where oil and gas industries make up a significant part of the economy. Colorado Gov. John Hickenlooper (D) and Montana Gov. Steve Bullock (D) are ardently pro-fracking. Even California Gov. Jerry Brown (D), caricatured as the ultimate 1970s liberal and who has called for urgent action on climate change, signed a measure in 2013 regulating the fracking industry. The first drilling in California is likely to begin this year.

Early in Obama’s first term, the intraparty tension cost the White House a key policy priority. The Democratic-led House passed cap-and-trade legislation by a narrow margin, with several
energy-state Democrats voting no. Despite a 60-seat Democratic supermajority in the Senate, the bill never stood a chance because Democrats such as Landrieu and Pryor would never have voted for it. (When he first won his Senate seat in 2010, West Virginia Democrat Joe Manchin III ran a campaign ad in which he took a shot, with a hunting rifle, at the cap-and-trade bill.)

The disconnect between donors who live in big cities on the coasts and elected officials who have to balance budgets and create jobs in energy-producing states causes tension within the party.

“For us, it’s not a social good. For us, it’s our livelihood,” Kenney said of oil and gas exploration, which makes up 11 percent of Colorado’s gross domestic product. “I’d politely suggest they send their checks and let us figure out our public policy,” he said of donors who think otherwise.