Lawmakers from major farm states, shaken by a preliminary World Trade Organization ruling against the government's multibillion-dollar subsidies to the cotton industry, warned on Tuesday that the action could deal a severe blow to agribusinesses and farmers nationwide.
"This has the potential to have extraordinary consequences up and down every main street in rural America," Senator Kent Conrad, Democrat of North Dakota, said of the W.T.O. decision, which ruled in a case brought by Brazil that the subsidies paid to the United States cotton industry violate global trade rules.
The ruling calls into question the 2002 farm bill, which increased subsidies to $19 billion a year for the country's biggest farmers who grow commodity crops like cotton, corn, rice, wheat and soybeans. The United States said such direct payments did not distort world trade. Brazil successfully argued that because they were underwritten by taxpayer money, American farmers grew more crops that flooded world markets, brought down world commodity prices and undercut farmers in Brazil.
As lawmakers demanded serious action to respond to the ruling, the White House said that it would not make any unilateral concessions but instead would work with Congress and the agriculture sector to defend the United States' farm interests.
The case eventually could compel Washington to cut farm subsidies and force the United States, Europe and other wealthy economies to make greater concessions to poor countries at global trade talks.
Policy makers and officials were on the defensive, saying it was unfair for Brazil to single out the United States for its cotton subsidies when other countries have their own unfair trading practices like high tariffs and different scientific standards for agricultural imports. All those issues, they said, should be the subject of negotiations, not cases before the W.T.O.
In a show of bipartisanship, Representative Bob Goodlatte, Republican of Virginia, and Representative Charles W. Stenholm, Democrat of Texas, the ranking members of the House Agriculture Committee, said the decision had to be appealed.
"Changes to countries' agricultural policies should come through the give and take of negotiations, not through decisions that do not appear based on W.T.O. rules," they said.
But Brazil filed its case against the United States precisely because its officials said they were frustrated that global trade talks aimed at reducing or eliminating agricultural subsidies of wealthy nations had been blocked.
Spreading the pain, Brazil has also filed a case at the W.T.O. against the European Union for its sugar policies. Over the last two weeks, the Europeans have been debating how to reform their policies, and reduce their subsidies in advance of any negative ruling against them.
The ruling on cotton has revived the debate in Congress over whether to pay farmers for producing food or for conserving the environment. If the preliminary ruling holds, conservation payments could become the best way to support farmers without breaking trade rules.
Allen F. Johnson, the chief agriculture negotiator for the trade representative's office, said Tuesday that if the ruling did hold it "would have a negative effect on how officials see the W.T.O. and free trade in general."
In their annual spring meetings last week, economists at the World Bank said that 144 million people could be lifted out of poverty if rich countries reduced or eliminated the $300 billion rich nations pay their farmers in subsidies and support.