Phil Radford, executive director of Greenpeace, stands in front of the Capitol to protest the influence of oil companies on Congress. (Chris Kirk / Medill)

WASHINGTON — About 100 demonstrators dressed up like referees and blew whistles outside the Capitol Tuesday to “call foul” on Congress, which they said has been bought by big oil companies that spend millions on lobbying and campaign contributions.

The protesters applauded the Obama administration’s decision last week to reject a proposal to build the controversial Keystone XL pipeline from Canada to Texas. However, they said the victory was only a step in the continuing effort to untangle government from well-funded oil companies.

This is one small battle that is part of a bigger war,” said Lillian Molina, the environmental justice director of the Energy Action Coalition, an environmentalist activist organization. “We know the fight is not over.” Demonstrators blew whistles in agreement.

The demonstration began at noon on the west lawn of the Capitol, where protesters waved red penalty flags,  raised a large sign that read “FOUL PLAY,” ”

Speakers, including Phil Radford, executive director of Greenpeace, accused oil companies of corrupting democracy by spending millions in campaign contributions and lobbying. They also accused congressmen of returning the favor by subsidizing oil.

“They’re listening to their friends in the oil industry, who have bought them,” Radford said.

Radford called the trade organization American Petroleum Institute “one of the biggest liars out there,” saying it lied about the effect the Keystone XL pipeline would have on jobs. He cited a study from the Cornell University School of Industrial and Labor Relations that concluded the pipeline would destroy jobs while increasing gas prices.

The demonstrators dwindled to a few dozen and took the Metro to the American Petroleum Institute to continue protesting.

“We welcome public debate on the issues,” said Reid Porter, Media Relations Representative, in an e-mailed statement. “One of the biggest issues at hand is job creation. We can’t be serious about job creation if we take a pass on the largest project that would create jobs, the Keystone pipeline.”

Porter echoed a statement made by Jack Gerard, CEO and president of the American Petroleum Institute, following the Obama administration’s announcement last week that it would reject the Keystone Pipeline proposal: “This is all almost too hard to believe. It makes you really question how serious the President is about job creation. We have to ask, Mr. President, what are you thinking?”

In the administration’s announcement, Deputy Secretary of State William J. Burns said there was not enough time to thoroughly assess the proposal before the Feb. 21 deadline Congress set in December.

Within minutes of the announcement, Republican congressmen vowed to fight for legislation that would allow the proposal to go forward, arguing that it would boost the economy. Republican presidential candidates have said they would reverse the decision if elected.

“Saying ‘no’ was the right thing,” said protester Carmela Ormando, 49, from Arlington, Va., “but I’m not confident it won’t resurface.”

The rally was organized by 350.org, an organization that advocates for caps on greenhouse gas emissions.