Environmental groups gathered on the National Mall in Washington, D.C. Sunday and marched on the White House for a climate change rally largely aimed at pressuring President Obama to reject the Keystone XL oil sands pipeline.

Organizers said 35,000 activists attended the rally, where speakers portrayed the battle over the pipeline as a struggle between grassroots green groups and deep-pocketed special interests.

“They’ve got the lobbyists. They’ve got the super-PACs. They made the campaign contributions. They’ve got this town in their pockets — they have got the situation under control. And then you show up. And then we show up. And we change the game,” Sen. Sheldon Whitehouse (D-R.I.) told the crowd not long before it marched on the White House.

Obama will decide whether the project goes forward because it crosses national boundaries.