Roughly 3,000 environmentalists rallied outside the White House Sunday to voice their opposition against the proposed Keystone XL pipeline.

The protest, which began at 3 p.m. ET in Washington, D.C.’s Freedom Plaza, was organized by climate change activists -- many under the banner of a group called 350.org.

Participants gathered in the Plaza, before moving the demonstration to the White House.

Together, they chanted and clapped while hoisting a giant mock pipeline over their heads.

U.S. President Barack Obama temporarily blocked the Keystone XL pipeline last January, citing environmental concerns with its proposed route, which would stretch from Alberta to Texas.

Activists say the pipeline, which would run nearly 2,000 kilometres and carry 700,000 barrels of bitumen each day, is an affront to the environment.

“It’s critical to life on the planet,” said Protester Creek Iversen. “It’s the most important battle right now. And I guess you can kind of see by the coalition of people that it’s starting to come together.”

Daniel Kessler, a media campaigner for 350.org, told CTV News Channel on Sunday that it’s time Obama address the issue.

“The election is over and now it’s time for the president to decide pretty shortly on the state of the Keystone XL pipeline,” said Kessler.

“It’s been hanging in limbo for a number of years and now it’s time to finally decide, once and for all, if this really dangerous tar sand pipeline is going to be built,” he said.

But pipeline builder TransCanada Corp. maintains that the Keystone pipeline will be one of the safest and most modern in North America. Failure to build the line would further prolong America’s dependence on foreign oil and deny Americans jobs and tax revenues, said company spokesperson Shawn Howard.

“Because they’re forcing American refiners to rely on oil from the Middle East and other areas of the world that are hostile to American values and interests,” said Howard.

“You can’t just pretend that you can turn off the oil switch today and that it’s not going to cause a massive disruption to our way of life.”

Because the project crosses the international border, the Calgary-based TransCanada must obtain presidential approval before moving forward with the project.

TransCanada submitted another permit application last May after redirecting the pipeline around Nebraska’s Sandhills, the portion of the line Obama was concerned with.

With the newly re-elected president settling in, both environmentalists and business advocates are clamouring to keep the president’s attention on the Keystone file.

The group is calling for Obama to prove his commitment to fighting climate change by rejecting the pipeline. Global warming is an issue Obama raised but waded carefully around during the campaign, stating action was needed but the economy would be his first priority.

In response to suggestions the pipeline would create jobs, Kessler said this is not the right way to do it. Instead, Kessler said the focus should be on creating jobs that are sustainable.

It is estimated that the $5.3-billion project would create roughly 9,000 jobs during the construction period.

Public attention turned to climate change again this fall when superstorm Sandy slammed into the United States’ East Coast. Some, including Helen Clark of the United Nations Development Program, pointed to Sandy as evidence of climate change. Others have dismissed the idea as giving climate change more credit than it deserves for the event.

“What we’re seeing is really extreme weather, really extreme temperatures. We’re seeing what the scientists predicted around climate change,” Kessler said, adding that more than 17,000 temperature records have been broken around the globe this year.

In an open invitation to Sunday’s protest, a number of well-known climate change activists signed off on a message suggesting that little has changed since Keystone’s first rejection.

“Here’s what hasn’t changed: Keystone XL is still a crazy idea, a giant straw into the second biggest pool of carbon,” the invitation said.

Among those who signed off on the message are authors Naomi Klein and Tzeporah Berman, as well as Michael Brune of the Sierra Club and climate scientist James Hansen.

Kessler said the organization will stage another protest to drive its message home early in the New Year. Approximately 20,000 people are expected to attend a rally in Washington set for President’s Day on Feb. 18, 2013.

With files from CTV Edmonton’s Amanda Anderson