WASHINGTON (AP) -- Democrats Barack Obama and Hillary Clinton are walking a delicate line as they promise to aggressively tackle global warming while trying to assure voters that they continue to believe in the future of coal.
In states like Pennsylvania, where voters will cast ballots this Tuesday, and in West Virginia, Kentucky, Indiana and Montana - upcoming primary states - coal sways voters.
While increased mechanization has produced a dramatic decline in coal industry employment, the numbers remain substantial. There are 47,000 coal workers in Pennsylvania and West Virginia and 21,000 in Kentucky, according to the National Mining Association. The three states are the country's biggest coal producers after Wyoming.
Both Obama and Clinton have rallied environmentalists with their promises to develop windmills, solar power and other renewable energy sources and order mandatory reductions in greenhouse gases from power plants to counter global warming.
It's an energy policy that would seem to target coal, which produces half the country's electricity but also nearly 2 billion tons of carbon dioxide, the leading greenhouse gas, each year.
Instead, "clean coal" has become the mantra of both candidates. Some environmentalists are not too happy with that.
"They keep using the term 'clean coal.' That's really an oxymoron," snaps Brent Blackwelder, president of the environmental group Friends of the Earth. "They absolutely are pandering the coal industry's propaganda that clean coal is the hope of the future. There's no such animal as clean coal."
Not all environmentalists are as critical, acknowledging that coal will remain an integral part of the country's energy picture. The two Democratic presidential aspirants' support for coal is outweighed by their strong push for renewable fuels and - unlike President Bush - their call for mandatory, economy-wide action on climate change.
"How they finesse things on the margin is up to them," said Cathy Duvall, the Sierra Club's national political director, as long as they also "talk about moving away from conventional coal ... and putting money into and investing in a renewable energy economy that will provide jobs."
Obama, by representing Illinois, a top 10 coal producing state, has a little more experience at it than Clinton. Fifteen months ago, he joined Republican coal-state Sen. Jim Bunning of Kentucky in calling for loan guarantees and tax breaks for coal-to-liquid processing plants.
Environmentalists protested and he modified his proposal to include a requirement that such plants have carbon-capture technology and produce 20 percent less greenhouse gases than conventional diesel fuel refineries.
In reality, there is little difference in the broad energy agendas of Obama and Clinton.
Both have endorsed Senate legislation that would cut greenhouse gas emissions by more than 70 percent by mid-century through mandatory pollution limits on power plants, transportation and industry. Both have called for a $150 billion, 10-year clean-energy research and development program.
But neither has embraced the call by Al Gore and many Democrats in Congress for a moratorium on new coal burning power plants until carbon capture can be commercially developed.
The coal states are pivotal not only in the Democratic primary but also in the general election in November. Gore and John Kerry carried two of them - Pennsylvania and Illinois - in the last two presidential elections, but both lost to President Bush in West Virginia, historically a Democratic stronghold.
Sen. John McCain, the presumptive Republican nominee, also has endorsed a limit on greenhouse gases, although one less aggressive, but views continued coal use as imperative to meeting future energy needs.
At stops in Pennsylvania, West Virginia, Montana and Wyoming, the Democratic rivals have been careful to tell voters they don't want coal to disappear. Frequently they couch it in terms of clean, green energy development and jobs.
"We could invest in renewable sources of energy and in clean coal technology and create up to 5 million new green jobs in the bargain, including new clean coal jobs," Obama declared at a stop in Charleston, W.Va.
Clinton also gave a nod to King Coal when she was in Charleston.
"I've been saying all along we should have clean coal, the cleanest coal possible," she told a high school gymnasium crowd. "If we're serious about investing in clean coal and clean energy, we can create 5 million new jobs in 10 years."
Is it what coal producers and users want to hear?
"Absolutely," said Joe Lucas, a vice president for the American Coalition for Clean Coal Electricity. "None of them are saying that we aren't going to need coal."
But Lucas, whose group is financed by coal companies, utilities and transportation interests, also compared the candidates' pitches to their embrace of corn-produced ethanol in Farm Belt states such as Iowa.
At times, walking the line between coal and environmentalists hasn't been easy, especially when the topic became mountaintop mining, a practice prevalent in West Virginia, where large areas of mountain tops are stripped away to reach the coal.
Clinton drew the ire of some environmentalists when in public radio interview there she said she was "concerned" about mountaintop mining but also viewed it as an "economic and environmental trade-off" that must be "looked at ... from a practical perspective."
Facing a group of environmentalists opposed to mountaintop mining at a meeting in the coal town of Beckley, W.Va., Obama also talked about the balance between economics and environmental protection.
"There are environmental consequences to coal extraction," said Obama, "just as there are with any energy source." That's just what some of the mine workers in the audience wanted to hear.
Associated Press writer Tom Breen in Charleston, W.Va., contributed to this report.