WASHINGTON — Vermont environmentalist Bill McKibben and Vermont Law School professor Gus Speth were among 65 protesters arrested Saturday in front of the White House, where activists began a two-week demonstration against the proposed mining and transportation of tar sands.

Each day for the next two weeks, environmentalists will stage sit-ins here, coordinated by the Tar Sands Action organization. The protests are timed to the pending release of a State Department final analysis of the environmental impact of the proposed Keystone XL oil pipeline, which would transport the tar sands, also known as oil sands, from Canada to Texas. Each day will bring a new wave of activists to participate in the sit-ins, a coordinated attempt to be arrested, which organizers say will draw national attention to the issue.

On Saturday, the Tar Sands Action sit-in began at 11 a.m. as protesters who had volunteered to be arrested lined up and sat on the sidewalk in front of the White House. Other protesters who had not signed up to be arrested remained across the street in Lafayette Park.

The protesters in the sit-in held signs that read “Climate change is not in our national interest” and “We sit-in against the XL pipeline. Obama, will you stand up to big oil?” They chanted slogans, too, yelling, “Hey-hey! Ho-ho! Keystone oil has got to go!”

Organizers say the two-week protest will be the largest civil disobedience action taken by environmentalists in the U.S. Leaders said more than 2,000 people have signed up with the Tar Sands Action group to participate in the ongoing protest.

McKibben, a nationally known environmentalist and author from Ripton, was one of the protest leaders and is founder of the grassroots climate campaign 350.org.

“I think it’ll send a message that there’s deep and powerful support for Obama to do the right thing,” McKibben said Saturday, prior to his arrest.

The protest, he said, is an effort to compel President Obama to fulfill a campaign promise. The president, McKibben said, “proclaimed, the day he was nominated, that with his arrival ‘the rise of the oceans would begin to slow and the planet begin to heal.’ This is his opportunity to show that he meant it.”

The proposed pipeline has attracted much controversy and attention. It would carry a type of oil produced from oil sands, starting at its Canadian extraction site in the Alberta province and traveling southward to Texas. Environmentalists say that mining and drilling for the oil sands requires an enormous use of energy resources, far more than is needed to drill for liquid oil. Additionally, they said, the petroleum that is produced from the sands is highly corrosive and would cause leaks in the pipeline. Because of all the energy required to extract the oil from the sands, the process has a much larger carbon footprint and produces more greenhouse gases than does regular oil, environmentalists say.

But TransCanada, the company that would build and operate the pipeline, and the American Petroleum Institute – the American oil and gas industry trade association – cite studies saying the oil is no more corrosive than oil the U.S. has used for years, and greenhouse gas emissions from oil sands are less than 1 percent of estimated global greenhouse gas emissions. TransCanada also plans to use the newest technologies to prevent leaks in the pipeline, and to continuously monitor the system to shut it down if they detect a drop in oil flow because of a leak.

TransCanada filed its proposal for the pipeline with the State Department in 2008. The agency will make its final ruling later this year. If other agencies object, Obama would make the final decision.

Both the oil and gas industry and environmentalists have issued calls for action from Obama.

The American Petroleum Institute says granting approval for the project would allow the president to deal with another pressing problem: the 9 percent unemployment rate. “You’re looking at a project that has the ability to bring (20,000) jobs,” said Cindy Schild, refining issues manager for the American Petroleum Institute. “President Obama was out on his bus tour talking about being ready to sign off on projects that are going to create jobs. Here’s the opportunity to do that.”

But McKibben disagreed. “There are so many more jobs to be created the day we get serious about getting off fossil fuels,” he said. “Everybody knows that wind and sun are where the jobs are . . . . If we go whole hog producing our power from the sun, we’re talking about jobs that number in the millions, if not tens of millions.”

On Saturday, shortly after the sit-in began, the U.S. Park Police issued three warnings over a megaphone, each warning three minutes apart. Then, at about 11:40 a.m., they started arresting protesters. By 1:15 p.m., all 65 participants in the sit-in, including Vermonters McKibben and Speth, had been arrested.

The mood was calm and dignified throughout the day, even during the arrests. In fact, the protesters were almost cheerful. The Tar Sands Action website had requested that volunteers be “dignified in dress and demeanor – these are serious issues, and we want to be taken seriously.”

As the arrests were taking place, the action was met with cheers and applause from those in front of the White House and in Lafayette Park. “You’re a hero!” someone called out as a woman was arrested.

The protesters deliberately mobilized in areas that are restricted. The 1600 block of Pennsylvania Avenue is under the jurisdiction of D.C. Metropolitan Police, but the White House sidewalk and Lafayette Park across the street are the jurisdiction of the U.S. Park Police. Groups larger than 25 or people carrying signs must keep moving along the sidewalk, in order to keep it open for tourists and maintain the scenic value of the area and the White House. Failure to do so can result in arrest.

On Saturday, even environmentalists across the Atlantic found a way to be involved in the protest.

Environmentalists in Germany gathered at the Canadian embassy in Berlin for what they dubbed on Facebook the “Tar Sands Bike Tour,” a tour of oil sands involvement in Berlin, with stops at gas stations, embassies and ministries and finishing with an address aimed at Obama at the Brandenburg Gate.