The National Association of Home Builders, one of the largest lobbying organizations in Washington, is arguing that the proposed building codes amount to an unfair and unnecessary increase on the cost of buying a home. Jerry Howard, NAHB’s chief executive, “adamantly opposes” efforts by Sens. Rob Portman (R-Ohio) and Jeanne Shaheen (D-N.H.) to require the Energy Department set targets for new homes and commercial buildings to stop wasting energy. “We don’t think that the Department of Energy should be coming in on top of state and local energy regulations and telling [them] how homes need to be built in their jurisdiction,” he said.

The bill, which binds together 50 energy-related proposals from both Democrats and Republicans, represents the best chance for major energy legislation to pass the Senate during the current congressional term. Shaheen blames the home builders for scuttling efforts to pass new building codes into law. “This special interest group should not be allowed to derail meaningful bipartisan action on energy efficiency in Congress,” she said.

Senate Energy and Natural Resources Committee Chair Lisa Murkowski (R-Alaska) said she decided to take out the building codes from her package with ranking member Joe Manchin III (W.Va.) out of concern it could tank the bill. “The subject of building codes has been controversial for a long time,” she said, though a similar provision was included in an energy package that passed the Senate in 2016. “At the end of the day, I decided I would take it out, knowing there would be opportunity for an amendment.”

The latest spat between home developers and energy efficiency advocates may now spill onto the Senate floor, as lawmakers prepare to debate whether to insert the building codes provision into the broader energy bill.

The package includes several provisions from a bill put forward by Portman and Shaheen, including measures to expand the Energy Department’s efforts to help manufacturers reduce energy waste and to train workers. But it left out the building codes provision that would have delivered the bulk of the Portman-Shaheen bill’s potential energy savings. The building code proposal was hailed by green groups such as the Environmental Defense Fund and business groups such as the U.S. Chamber of Commerce. The codes would not be mandatory unless states and municipalities decide to adopt them. Portman calls his proposal a “common-sense” approach that “will lower energy costs for American consumers and ensure that homes and buildings across America are built in a more energy efficient manner, not by mandates but by incentives.”