“What we’re going to see in this cycle is a lot of bitterness. … It’s going to be more partisan than it’s ever been,” said GOP environmental strategist Chelsea Maxwell. “So the energy and environment issues will definitely creep into that.”

It goes against conventional campaign wisdom — environmental issues rarely play a large role in shifting the electorate.

But this year, the conversation has taken a new turn. The message of nearly all campaigns nationwide is jobs with a capital “J.” Republicans have spent lots of time and effort targeting the “job-killing EPA” for a landslide of regulations that they say hurt businesses and the American economy with dubious returns on health.

While President Barack Obama’s eventual Republican opponent is by no means clear yet, insiders on both sides of the aisle say that the divide between the parties on environmental and energy issues will be clear, even as both sides inevitably move toward the middle to grab moderate voters.

“Regardless of who the candidate is, it will be the subject of debate and focus of the campaign, only because there is a lot on the EPA plate, so to speak,” Maxwell said. And there “is a lot of mobilization of the left,” and it will be pushing Obama.

In 2008, Sen. John McCain (R-Ariz.) and then-Sen. Obama “had essentially the same position … on the biggest environmental issue out there, which was global warming,” and Obama took positions to neutralize some issues, such as agreeing to consider expanded offshore drilling, said Daniel Weiss, director of climate strategy at the Center for American Progress Action Fund.

“That will be very different in 2012,” Weiss said. “The Republican candidates … have uniformly opposed EPA rules. They are undoubtedly going to use these rules as a cudgel to attack President Obama as being anti-jobs.”

Mitt Romney has shifted to the right on environmental issues: In October, he said he is skeptical of climate change science, and he has promised to reverse the Obama administration’s finding that carbon dioxide is a danger to public health, making it subject to Clean Air Act restrictions.

Romney touts his decision not to sign up for a regional cap-and-trade agreement, though he imposed carbon dioxide rules on Massachusetts utilities. Meanwhile, in an inconvenient fact for the GOP primary, EPA’s air chief, Gina McCarthy, once worked for Romney.

If the nominee for the GOP is Herman Cain, Rick Perry or Newt Gingrich, and “they call for abolishing EPA or severely, radically changing it … I think that it could become a higher issue. And frankly, I think that it might play to Obama’s advantage,” Clean Air Watch President Frank O’Donnell said.

Some Republicans agree and say that the GOP focus on the EPA as a job-killing agency may not play well in a presidential election.

“If I were talking to the Republican candidates … I would say the notion of disbanding [the] EPA is a bad idea — it feeds into this notion that Republicans are crazy people,” energy industry attorney Patrick Traylor, who is a partner Hogan Lovells, said at an Oct. 20 Environmental Law Institute meeting.

William Reilly, who headed the EPA under former President George H.W. Bush, recently came out swinging at Republican efforts to halt EPA regulations, saying that “significant majorities [of Americans] support air and water quality laws. That has been consistently true since the early 1970s, through the Arab oil embargo, high oil prices and recessions.”

“Polling numbers do not explain how EPA, almost uniquely among federal agencies, has become such a lightning rod for many politicians,” Reilly said, asking Republicans to “charge out and remind the country that Republicans … care about … demagogic assaults on regulators who are doing the job Congress gave them implementing George Bush’s Clean Air Act.”

But it is not Republican interests alone that will focus the presidential race on environment and energy issues.

Last week, the State Department delayed the Keystone XL pipeline decision until 2013, and critics immediately pointed to the 2012 election.

The decision came a week after environmentalists protested at the White House, cresting a months-long campaign to position the decision as a potential campaign problem for the president. Having a core constituency focused on communicating disappointment to the White House rather than raising money and scouting for votes could hinder the campaign, environmentalists said.

“It’s obvious that a lot of the environmental activists … view Keystone as a litmus test,” O’Donnell said. “But if for some reason it got the green light, what are they going to do — just not be enthusiastic? That’s the ultimate problem that the green lobby has.”

He pointed to the administration’s decision to pull back on EPA’s ozone rule. “They looked around and said, ‘We’ve got nothing to lose here politically.’”

Nevertheless, environmental and regulatory support groups, such as the League of Conservation Voters, Sierra Club and the Coalition for Sensible Safeguards, are already running ad campaigns to support EPA rules and target close House races and certain senators.

Ads generated by special-interest campaign funding are, in fact, likely to be a key factor in keeping environmental regulations a part of the 2012 race, considering the expected massive increases in corporate funding the 2010 Citizens United v. Federal Election Commission Supreme Court decision and the subsequent explosion of super PACs. A super PAC can raise unlimited amounts of money but cannot coordinate directly with a campaign.

“Many Republican professionals talk about the great Obama money machine, ignoring the fact that … if you add it up,” GOP-leaning industry funders “could easily swamp what President Obama and their allies” spend, Weiss said, noting in particular the American Petroleum Institute’s new PAC.

The oil and gas industry, the mining industry and the electric utility industry are all big-money sectors to watch, including several newly formed PACs.

As of Oct. 31, the Center for Responsive Politics, which tracks FEC filings, showed more than $11.6 million in spending from the oil and gas industries, with 12 percent going to Democrats and 88 percent to Republicans.

But that number is likely to rise exponentially when the campaign gets under way.

During the 2008 presidential election, the oil and gas industry spent over $37 million on election donations. That year, Obama took in just over $916,000 from the oil and gas industry, an amount topped only by McCain, who raised $2.5 million from the industry.

In 2010, the total contributed by the industry dropped to almost $32 million, but outside money saw a more than 1,500 percent increase — to $2,305,566 from $139,392. This year, top companies ExxonMobil and Koch Industries have already spent more than $759,594 and $619,850, respectively.

Mining made a similar jump, with donations nearly doubling to $11 million in 2010 — an off year — largely through outside spending groups, according to CRP data. Mining funds usually balance out at around 75 percent Republican to 25 percent Democratic donations and were exactly that in 2010. As of Oct. 31, however, with nearly $3.7 million in donations already parceled out, the industry was running a 90-10 split favoring the GOP.

Electric utilities have traditionally run about even in donations between parties, with around $20 million in donations. Thus far in the 2012 cycle, however, having spent $6.8 million, they are running 62 percent GOP to 38 percent Democratic, according to CRP data.

The utilities focus most of their funds on lobbying, having spent more than $105 million so far in the 2012 cycle.

The environmental lobby, by contrast, spent over $12 million in 2011 on lobbying. Environmental campaign contributions so far in the 2012 cycle are at around $500,000, split 90 percent to Democrats and 10 percent to Republicans. In 2008 and 2010, they hovered at around $5 million total, though the lobby saw about a $1 million boost in both PAC and outside money in the 2010 cycle.