"It's time for the president to stand up," he said, describing the 1,000-plus mile pipeline as "one of the largest carbon bombs in history." Some climate scientists say the production of tar sands emits more greenhouse gases than that of conventional crude oil. Supporters, including the oil industry, say it would reduce U.S. dependence on unstable foreign sources of oil.
Among the protesters were senior citizens in wheelchairs, a dad from Indiana carrying a toddler, women from a Unitarian church in Corvallis, Ore., and college students, including Florida's Molly Kampmann, who was holding a picture of a pipeline with the caption: "This is why I'm hot."
Others held placards saying, "Read my lips: no new carbons," and "We're in a climate hole: stop digging." Another, referring to a method for extracting natural gas, said: "Don't be frackin' crazy."
"We're right in the path of sea level rise," said Mark Geduldig-Yactrosky of Portsmouth, Va., explaining his concern about climate change. "We're a low-lying area. We have rising oceans and subsiding lands. So that personalizes it for us."
Burlington, Vt., resident Michael Ware, holding a "Stop Vermont Yankee" banner, said last year's extreme weather convinced many Americans that climate change is serious. "What will Vermont, what will any state, look like in 20 years?" he asked.
"I have six grandchildren, and I want them to have a habitable planet," said Linda Britt, who came from Ann Arbor, Mich., with other grandparents.
Obama has pledged repeatedly to tackle climate change. In his State of the Union Address, he gave Congress an ultimatum: If lawmakers don't act, he will. Protesters say they are holding him to his word. They want him to not only reject the pipeline but also set limits on carbon pollution from both new and existing power plants. Last year, the EPA proposed limits only on new plants.
In January 2012, Obama rejected the initial 1,700-mile Keystone XL pipeline from Alberta, Canada, to Port Arthur, Texas, saying he needed more time for environmental review. Since the project crosses a U.S. border, it needs a permit from the State Department, but Obama has said he'll make the final call.
The project's developer, Calgary-based TransCanada, has since broken the project into two parts. It received approval last year from the U.S. Army Corps of Engineers to begin construction of the 485-mile, $2.3 billion southern leg of the project from Cushing, Okla., to the Gulf Coast. Obama's pending decision involves the 1,179-mile, $5.3 billion northern leg, from Alberta to Steele City, Neb.
The pressure on Keystone has intensified since Nebraska Gov. Dave Heineman, who like Obama had rejected the initial route, notified the president last month that he'd approved the revised route through his state. Heineman, a Republican, said it would avoid environmentally sensitive areas and bringjobs and other economic benefits.
TransCanada President Russ Girling, who hailed Heineman's reversal, traveled to Washington earlier this month to lobby personally for the billion-dollar project.