The crowd of wealthy Democratic fundraisers and donors who protested outside President Obama's $5,000-a-head San Francisco fundraiser last week - dubbed the "powerful and the POd" - aren't going away.

Josh Newman and Amanda Ravenhill of San Francisco stand atop a Keith Haring sculpture outside the W Hotel - site of President Obama's fundraiser - to protest the Keystone XL pipeline. (Lea Suzuki / The Chronicle) This week, they're planning a high-profile reprise at the White House to again deliver a loud message on an environmental issue that could become a major political liability for Obama in the 2012 election: the proposed construction of Keystone XL, the controversial $7 billion, 1,700-mile pipeline that would carry crude oil from Alberta, Canada, to refineries in Texas.

Environmentalists are appalled by the plan to ship dirty tar sands oil across the nation, while unions and energy companies promote the jobs that would be produced by the project. The Obama administration has not given its final blessing, and any decision is sure to alienate key constituencies.

Obama "is going to reveal his character" when it comes to his decision regarding Keystone, said Michael Kieschnick, head of CREDO Mobile and founder of Working Assets - businesses that have donated $60 million to Democratic causes.

On to Washington

Kieschnick was on the front lines last week when 1,000 protesters gathered outside Obama's fundraiser at the W Hotel. Now he will travel to Washington to join some of the same generous Bay Area-based Democratic donors - including Susie Tompkins Buell and Anna Hawken McKay, wife of philanthropist Rob McKay, whose father founded the Taco Bell empire - to again protest the pipeline.

They plan to circle the White House with an expected 5,000 protesters who will dramatize their opposition to the pipeline on Sunday, Nov. 6 - exactly a year from the 2012 election.

"I think this is a huge issue about our future, about the planet, not just America," said Buell, a longtime friend and backer of former presidential candidate Hillary Rodham Clinton. It's estimated that Buell has raised more than $1 million for Democratic causes.

The opposition of such high-profile Democrats to the project proposed by TransCanada dramatizes the political challenge for Obama. With the first votes to be cast in the 2012 primaries starting in just two months, the Keystone issue pits some of his most powerful supporters against major labor and energy interests.

Opponents say the project would damage the environment for generations, prompting devastating spills of the corrosive oil and undermining U.S. clean-energy efforts.

Supporters argue the pipeline could produce thousands of well-paying jobs and stimulate the economy at a time of stalled growth.

The White House has said the State Department has the first say on a go-ahead for the international project; Secretary of State Clinton has already hinted she is "inclined" to approve it.

But Obama will make the final call - and is being pressured to do so before the end of the year.

TransCanada pitches the project as a way to wean America off of oil imported from hostile countries and says most of the oil would be used here in the United States. But the pipeline extension would also connect Alberta's tar sands to the global market, opening up a world of potential customers.

To TransCanada - and the Canadian government - that means more jobs. The company's head of oil pipeline operations recently called the tar sands Canada's main engine of economic growth for the next 50 years; it would employ 20,000 Americans, according to the company.

"The economic benefits for both Canada and the United States of the oil sands development can't be overestimated," Cassie Doyle, Canada's consul general in San Francisco, said at a Commonwealth Club debate on the project. "It is a major economic driver."

'Not just about jobs'

Tupper Hull, spokesman for the Western States Petroleum Association, called the project "a no-brainer."

"This is not just about jobs. There are a huge number, and a huge amount of economic stability and growth, that could be achieved with this," he said. "And it's also about energy security."

Stretching beneath northern Alberta, the sands represent the world's third largest oil reserves - roughly 170 billion barrels - ranking behind Saudi Arabia and Venezuela.

But the oil comes in an unusual form: The tar sands are a mixture of sand, clay, water and bitumen, a dense and viscous fluid that can be processed into a form of synthetic crude oil. Sands close to the surface are strip mined, with 2 tons required to produce a single barrel of synthetic crude. Deeper than 245 feet, the sands are left in place, and steam is pumped underground to make the bitumen less viscous so it can be piped to the surface.

Environmentalists such as Kieschnick argue the vast, open pits left by tar sands development are a disaster. They also consider the sands a threat to the climate, because the process of mining the sand, separating out the bitumen and processing it into synthetic crude takes more energy and produces more greenhouse gas emissions than simply pumping oil from the ground.

If it goes through, he said, "all the fuel-efficiency standards - everything this administration has done right (on climate change and global warming) is eliminated. ... Everything good will be wiped out if we develop the tar sands."

Hull disputes those claims, saying, "Canada has a very strong environmental ethic as a country ... and federal and state governments have taken major strides to reduce the environmental impact and the carbon emissions associated with oil sands development."

Deep disillusionment

For Kieschnick, the pipeline also has come to symbolize the deep disillusionment that many environmentalists now have with the president.

They were horrified when Obama abandoned efforts to create a cap-and-trade system for limiting greenhouse gas emissions. And they accused him of caving to big business when he stopped the Environmental Protection Agency from instituting new rules to cut smog.

"There's a sense of, 'Look, you haven't given us a whole lot during this administration. It's time to give us something significant, and this is it,' " said Michael Marx, director of the Sierra Club's Beyond Oil Campaign. " 'If you don't give it to us, it's such a sign that you've betrayed your promises to us.' "

Politically, some analysts say that in an election in which independent voters could call the shots, the president has a tough calculation to make.

Morley Winograd and Michael Hais, authors of the new book "Millennial Momentum," said that with the nation's largest generation - 95 million "Millennials" born between 1982 and 2003 - facing an unemployment rate that is twice the nation's as a whole, the economy and jobs may trump the environment.

The message among their ranks - as seen in many of the Occupy protests - is: "We're looking for jobs," Winograd said.

Marx counters that for millions of Americans who cast votes for Obama in the 2008 election, Keystone brings home whether the president has really delivered the "hope and change" he promised.

"The reality is, when faced with a mediocre choice and a horrible choice, we're pragmatists," he said. "But campaigns are won and lost by the passions of people."

That means that some of Obama's most loyal voters may see Keystone as a touchstone.

"If he does the right thing," said Kieschnick, "he'll be worth fighting for again."