A bipartisan effort to exempt animal manure from cleanup liability under the federal Superfund law is facing major hurdles in both the House and Senate, with the chairmen of three key committees opposing the plan.

Later today, lawmakers from both parties will reintroduce legislation that exempts animal manure from the definition of a hazardous substance under Superfund. Proponents of the measure, including the agriculture industry and lawmakers from farming states, argue that Congress never intended for manure to be included in the Superfund law when it was passed in 1980.

Supporters say that passage of the legislation would limit expensive penalties and cleanup liability for farmers. Backers include Sens. Blanche Lincoln (D-Ark.), Ben Nelson (D-Neb.), Chuck Grassley (R-Iowa) and Chuck Hagel (R-Neb.). In the House, Agriculture Chairman Collin Peterson (D-Minn.) will sponsor the bill.

“This legislation will ensure that [farms] are not burdened by cumbersome regulation and litigation as a cost of running their businesses,” Nelson said in a statement.

But critics of the bill say that Superfund law has been applied to only the most egregious of polluting farms — large-scale facilities known as concentrated animal feeding operations. Such facilities, dubbed “factory farms” by critics, are major sources of water pollution, environmentalists allege.

The critics charge that the bill is little more than an attempt by big agriculture to forestall expensive lawsuits such as the one now pending in federal court by the state of Oklahoma against Arkansas CAFOs.

The bill will have to move through at least three committees in the House and Senate where the chairmen actively oppose the plan. House Energy and Commerce Chairman John Dingell (D-Mich.) last year called an earlier version of the bill an “outrage,” and Senate Environment and Public Works Chairman Barbara Boxer (D-Calif.) — a strong supporter of the Superfund program — is thought likely to oppose it as well.

Spokesmen for the lawmakers didn’t respond to requests for comment, but Ed Hopkins, director of the Sierra Club’s Environmental Quality Program, noted that Dingell and House Transportation and Infrastructure Chairman James Oberstar (D-Minn.) — who also has jurisdiction over the bill — last year circulated a “Dear Colleague” letter opposing the bill in the 109th Congress.

Despite the opposition by key lawmakers, Hopkins said the popular support the bills earned in previous Congresses — including more than 125 co-sponsors from both parties in an earlier House version — means the measure isn’t dead yet. “Any time a bill has that many co-sponsors it’s a cause for concern,” he said.

An aide to Peterson said that the bill already has 59 co-sponsors and predicts “people will jump on pretty quickly.”

The opposition to the bill by the committee heads has prompted speculation that proponents could try to attach the legislation to the upcoming farm bill, but Hopkins says that would require the approval of the relevant chairmen, which is unlikely.

The Peterson aide was unaware of any attempt to use that tactic.