Thousands of protesters rallied in Washington Sunday to revive their call for U.S. President Barack Obama to block the proposed Keystone XL pipeline, a massive project that would transport crude oil from Alberta to the United States.

A line of demonstrators marched toward the White House carrying an inflatable mock pipeline overhead.

The hotly contested pipeline would carry bitumen from the Alberta oilsands to refineries in Texas.

Ten months ago, Obama put the project on hold, citing concerns it could threaten an environmentally sensitive area in Nebraska.

Since then, however, Calgary-based TransCanada, the company behind the pipeline, has proposed a new route that avoids the area.

And with Obama elected to a second term, the project's supporters expect he'll now approve the $7-billion project.

Extra capacity not needed: report

The government of Prime Minister Stephen Harper is eager to see the pipeline built, arguing the project will create thousands of jobs and pump billions of dollars into the Canadian economy while also helping the U.S. secure its energy needs.

A report commissioned by the U.S. government itself rebuts that idea, however, saying that there is already enough pipeline capacity to the U.S. to deliver petroleum from Western Canada until at least 2030.

Some critics of the pipeline also say that Alberta's oilsands output should be refined in Canada, keeping those jobs here, while others don't want to see any ramped up production of Alberta's bituminous oil.

There's also questions about how much of the oil piped to the U.S. would actually remain there. Oil companies' own plans show they intend to export much of the refined products to Asia and Europe.

Obama, who is currently in southeast Asia for a three-country tour, wasn't present for Sunday's protest.

With files from CBC News