WASHINGTON _ Several leading American environmentalists were among 48 people arrested outside the White House on Wednesday as they protested TransCanada’s proposed Keystone XL pipeline, a flashpoint for the U.S. climate change movement.

After the activists gathered outside the White House’s northernmost wrought-iron fence, along a stretch of Pennsylvania Avenue where protests are prohibited, police began their methodical arrests as supporters chanted: “Hey, Obama, we don’t want no climate drama.”

Among those arrested were Michael Brune, the executive director of the Sierra Club; James E. Hansen, a prominent climate scientist; Bill McKibben, a vocal anti-Keystone XL activist; and environmental lawyer Robert F. Kennedy Jr.

Brune is the first Sierra Club leader in the organization’s 120-year history to be arrested in an act of civil disobedience after the Sierra Club suspended its longtime policy against the practice due to Keystone XL.

Actress Daryl Hannah, who was arrested in August 2011 at a similar anti-Keystone protest outside the White House, was also apprehended.

Some of the protesters had tied themselves to the fence on a grey, drizzly day while others simply refused to move when police repeatedly asked them to vacate the sidewalk.

The protest came the day after U.S. President Barack Obama delivered his fourth State of the Union address. While he reiterated his call for swift action to combat climate change, Obama made no mention specifically of Keystone XL.

John Kerry, Obama’s new secretary of state, said last week that a decision on the pipeline was coming soon. Kerry, a fierce climate hawk during his 28 years in the U.S. Senate, gave no indication of his stance on Keystone in a joint news conference last week with Canada’s foreign affairs minister, John Baird.

The State Department will decide the fate of Keystone XL since it crosses an international border.

The controversial pipeline would carry bitumen from Alberta’s carbon-intensive oilsands to the U.S. Gulf Coast. Environmentalists view the pipeline as a symbol of “dirty oil,” and have been urging the president to make good on his climate change rhetoric by nixing TransCanada’s latest permit application for the $7 billion project.

“The Keystone pipeline has become the purest test that there’s ever been on whether the president is serious about doing something about climate change or not,” McKibben told the crowd before walking across Pennsylvania Avenue to tie himself to the White House fence.

Kennedy Jr. told the gathering that he predicts the anti-Keystone forces will prevail.

“The science is clear,” he said.

“Climate change is not just an economic issue, it is a moral issue. I do not believe that Keystone XL will happen. I believe that President Obama and Secretary Kerry will do the right thing. And we need to show our support.”

As the activists were hauled off to jail, the American Petroleum Institute and the AFL-CIO, a prominent U.S. labour federation, urged Obama to green-light the project.

The wait has gone on long enough, said Sean McGarvey, the president of the AFL-CIO, vowing to escalate efforts to convince Obama to approve Keystone XL.

Jack Gerard, CEO of the petroleum institute, said his group would start pouring more money into advertising and social media efforts to mobilize pipeline proponents.

He argued that Keystone XL offered Obama the perfect opportunity to achieve his goal of creating jobs for the middle class.

Environmentalists, meantime, are planning another protest at the White House on Sunday. It’s expected to draw thousands of protesters.

The U.S. ambassador to Canada said Wednesday that Obama’s State of the Union call for speedy action on climate change should be interpreted as a challenge to Ottawa as well.

Obama warned Congress on Tuesday to either agree to market-based solutions to climate change or he’ll use his executive powers to do it himself.

“We all need to do as much as we can. And that is true in your country and in mine,” Jacobson said in an interview with The Canadian Press.

“Obviously the more that the energy industry _ whether it is the oilsands in Canada or the energy industry in the United States, or any place else _ the more progress they can make to reduce greenhouse gas emissions, to reduce their consumption of water, to other environmental consequences, the better off we all are.”