Actually, the Keystone pipeline is just the most visible of their complaints. What they really oppose is the modern world and their fervent belief in global warming underlines their commitment to downsizing industrial civilization.

Washington Post:

But the demonstrators tried to send him a message nonetheless, carrying signs opposing not only the proposed pipeline from Canada to Texas, but also opposing hydraulic fracturing, or fracking, and coal plants. "Windmills, not oil spills," one placard said. Another said, "Fossil fuels? Fossil fools." And another: "Read my lips: no new carbons."

Leaders of the rally said they wanted to press Obama to follow up on the strong rhetoric in his inaugural address about the need to slow climate change. The official posters at the rally borrowed Obama's campaign slogan "forward." They read: "Mr. President, Forward - on Climate."

"Mr. President, we have heard what you've said on climate; we have loved a lot of what you've said on climate," said Michael Brune, executive director of the Sierra Club. "Our question is: What will you do?"

For many of the rally leaders, the first test will be whether the president and Secretary of State John F. Kerry approve a construction permit for the northern leg of the Keystone XL pipeline, which would carry crude from the oil or tar sands of Alberta to refineries on the Gulf Coast of Texas.

The energy-intensive methods needed to extract that crude emit more greenhouse gases than oil production methods from conventional reservoirs.

That last little tidbit is extremely deceptive. To state as fact that fracking emits more greenhouse gases than conventional drilling is wrong. The jury is still out:

Two groups of Cornell University researchers have split over the contribution to global warming by rising extraction of natural gas from shale beds through a process known as fracking.

Dueling papers in the journal "Climatic Change" dispute conclusions published in April that so-called unconventional gas production spews more heat-trapping compounds into the atmosphere than mining and burning coal.

The April research by Robert Howarth, a Cornell professor of ecology and evolutionary biology, and Anthony Ingraffea, a professor of civil and environmental engineering, overestimated leaks from fracked wells by as much as tenfold, Lawrence Cathles, a Cornell Geology professor, argues in a commentary posted online by the journal and provided by Cornell.

"In the short term, our energy needs should be satisfied mainly by those fuels having the fewest inherent environmental disadvantages," Cathles and his co-authors concluded. "Those preferred fuels include natural gas."

Howarth's study, published in "Climatic Change Letters" said as much as 1.9 percent of the gas in a well escapes to the atmosphere during fracking, compared with 0.01 percent when completing a conventional gas well. That ruled out gas as a "bridge fuel" as more renewable energy is developed, he said.

A more reasonable estimate of gas lost during fracking is 0.2 percent, Cathles said.

Sorry, but greens don't do "reasonable."

I would guess that chances of Obama's approving the pipeline stand at 50-50. He may allow the State Department to kill it - Foggy Bottom has to sign off on the project before it can be approved. Or, he may allow it to go forward without much fanfare.

He's already wasted more than 3 years in delaying approval.