Environmentalists battling the development of the Keystone XL pipeline will shift their focus away from the White House on Tuesday to a referee-themed rally on Capitol Hill featuring at least 500 people symbolically blowing the whistle on Big Oil's power over the U.S. Congress.

The grassroots organization 350.org is planning Tuesday demonstration that will begin at the Capitol, and end with a march to the American Petroleum Institute, the influential oil and gas trade association that is lobbying for the approval of the proposed 1,700-mile tar sands oil pipeline.

It will be unavoidable, very visible, and just disruptive enough to absolutely get the attention of the oil industry's representatives in Congress and put them on notice that the era of big oil corruption will soon be coming to an end, states a Web page about the demonstration. We're going to Washington DC to blow the whistle on Big Oil corruption in Congress.

The demonstration will feature 500 protesters wearing black-and-white referee shirts, blowing whistles, throwing penalty flags, and holding signs that call out individual members of Congress for the amount of money they have received from the fossil fuel industry, according to statement about the event. U.S. Sen. Bernie Sanders, I-Vt., Greenpeace Executive Director Phil Radford, and 350.org founder Bill McKibben are all scheduled to attend the demonstration.

Although President Obama rejected TransCanada's -- the Canadian corporation that proposed the project -- application for a permit to begin construction of the massive Alberta-to-Texas pipeline last week, the company will be allowed to reapply for the permit after it develops an alternative route around the Nebraska Sandhills. Opponents of the pipeline have argued that its current configuration could pose a potential hazard to Nebraska's Ogallala aquifer, which provides drinking water to eight states in the region.

Congressional Republicans initially attached a Feb. 21 deadline on the pipeline approval as part of the payroll tax package that passed in December. The Obama administration said the permit was rejected because the 60-day window did not give federal officials enough time to review alternative routes that would bypass the Nebraska aquifer.

Environmentalists have been speaking out against the Keystone XL pipeline for months. Tar Sands Action, along with a coalition of environmental groups, held a two-week protest in front of the White House between Aug. 20 and Sept. 3 that led to the arrest of more than 1,200 activists. On Nov. 6, thousands of demonstrators once again gathered at the White House and formed a human chain around the building as a symbol of protest.

In the U.S. House of Representatives alone, members received nearly $12 million from individuals and political action committees connected to the oil and gas industry between July 2009 and July 2011, according to an analysis by the non-partisan research organization MapLight. Of the 118 House members who counted the oil and gas industry among their top 10 contributing industry groups during that period, only two voted against the Feb. 21 pipeline deadline.