On the eve of a protest planned for March 2, Speaker Nancy Pelosi and Senate Majority Leader Harry Reid have offered new support to environmentalists hoping to force the Capitol Power Plant to abandon coal entirely. But the move could still face some important obstacles.

The plant, located a few blocks from the U.S. Capitol, provides heating and cooling for the Capitol, the Supreme Court, the Library of Congress, and various other buildings. While much of the fuel burned by the plant is natural gas, nearly half of it is coal. A 2000 attempt to change the facility to other fuel sources stalled after Democratic Senator Robert Byrd of West Virginia and Republican Senator Mitch McConnell of Kentucky wrote to the Architect of the Capitol to request that the upgrade be delayed until coal had received full consideration.

In a new letter to the Architect of the Capitol, Reid and Pelosi expressed a desire to find funding to retrofit the plant, if necessary, so it could operate just on natural gas. A protest at the plant is scheduled for March 2, and organizers are hoping for as many as 2,500 people.

McConnell had no immediate reaction. A statement from Byrd said he supported Reid and Pelosi’s suggestions that the Capitol architect explore ways to retrofit the plant. Byrd said that he’d been a “supporter” of coal at the plant and that it was “regrettable” that there had not been more investment in clean coal technologies. He urged Congressional leadership to aggressively support “additional efforts” to develop clean coal technology.

The coal for the plant is provided by International Resources Inc. and Kanawha Eagle mine, part of Peabody Energy.

According to the Center for Responsive Politics, Byrd has received at least $172,661 from campaign contributors in the mining industry, including at least $2,000 from donors at Peabody Energy.

McConnell has received at least $607,799 including at least $2,000 from International and $81,600 from Peabody.

Neither company has made any reported contributed to Reid or Pelosi.