WASHINGTON (NEWS1130) – Organizers expected tens of thousands of protestors in Washington Sunday, for what they called the biggest climate rally in US history.

It was primarily to protest the Keystone XL pipeline, which would carry Alberta bitumen to Texas refineries.

On Wednesday, meanwhile, a rally outside the White House led to 48 arrests including Robert Kennedy Jr. and Daryl Hannah.

Approving the Keystone XL pipeline is a step in the wrong direction, according to Daniel Kessler of 350.org.

The final decision will come down to US Secretary of State, John Kerry.

Patrick Michaels of the Cato Institute believes the decision has likely already been made, however.

“If they come out against it, they’re going to pay a very, big price,” Michaels said.

Prime Minister Stephen Harper has advocated for the approval of the pipeline several times.