In every American supermarket, labels tell shoppers where their seafood came from. But there are no such labels for meat, produce or nuts. Behind the contradiction is a lesson in political power in Washington, where lobbyists and members of Congress have managed to hold off the enforcement of a five-year-old law that required country-of-origin labeling on meat and produce as well as fish.

Now, with Democrats in control of Congress and mounting questions about the safety of food imported from China, proponents of the labeling law say they believe that they finally have momentum on their side.

After all, they say, at a time when consumers are ever more concerned about where their food is coming from, why not just tell them on the package?

"No. 1, there's a basic consumer right to know," said Michael Hansen, senior scientist at Consumers Union, an advocacy group that publishes Consumer Reports magazine and supports the labeling law. "People are more and more concerned about the food they eat."

But the labeling law has formidable foes, including the meat lobby, which so far has outmaneuvered its opponents on Capitol Hill. In the years since the labeling law was enacted as part of the 2002 Farm Bill, its opponents have successfully blocked all but seafood labeling from taking effect.

Opponents of the law say they believe that it is too onerous and expensive and is simply a way for American farmers and ranchers to block cheaper foreign competitors.

Besides, they contend, retailers can voluntarily offer country-of-origin labels, as they do with hormone-free milk and organic foods.

"No one was prohibited from putting labels on products," said former Representative Henry Bonilla, Republican of Texas, who as head of the appropriations subcommittee on agriculture pushed through delays of mandatory origin labeling. "If consumers wanted this, they could have demanded it."

Critics say meatpackers simply do not want consumers to know that an increasing amount of hamburger meat and produce is being imported.

The fate of the country-of-origin labeling, known as COOL for short, will likely be resolved in the coming months as Congress rewrites farm policy.

The battle over the labeling law comes at a time when American farmers are facing increasing competition from all corners of the world: soybeans from Brazil, wheat from Ukraine and apples from China, to name a few. American consumers, meanwhile, are eating more food grown and processed overseas.

During the last decade, the value of imported food has roughly doubled, to $65.3 billion in 2006.

The meat lobby has historically been a powerful and efficient operation in Washington, with deep ties to Capitol Hill and the Department of Agriculture. Along with the grocery industry, the meat lobby has waged an effective campaign to stymie efforts to carry out the law.

The law required country-of-origin labeling on beef, pork, lamb, fresh fruits and vegetables, seafood and peanuts. To date, the debate has mainly been driven by the meat industry, with the produce and peanut industries playing a much quieter role.

The biggest supporters of the labeling law in Congress come from Great Plains states where ranchers face stiff competition from Canada.

A central reason the seafood labeling was pushed through in 2005 was Senator Ted Stevens, Republican of Alaska, who was chairman of the powerful Senate Committee on Appropriations at the time. He went to bat for Alaska fishermen, who benefited from a provision in the law that fish and shellfish include not only country of origin but whether it was farm-raised or caught in the wild.

Today, both sides of the debate over origin labeling contend that the seafood labels support their arguments.

For instance, in March, the Food Marketing Institute, a trade organization, said seafood labeling had cost 10 times more than original estimates and failed to increase sales of American seafood.

But the United Fishermen of Alaska tell a different story, saying that origin labeling has increased demand and prices for their wild salmon. And with the current concerns over Chinese seafood, labeling of seafood gives consumers the option to buy something else, advocates say.

The push for origin labeling started in the mid-1990s, when cattle ranchers grew frustrated by the influx of imported beef, particularly from Canada, as a result of trade agreements that opened the border to imports.

The thinking behind the proposal was that, given a choice, consumers would likely choose products from the United States over imported ones, even if they cost more. But origin labeling is not just about patriotism or a desire to help American farmers. Part of its appeal is better food oversight, and some proponents of the measure have played to consumer anxiety by calling into question the safety of meat from places like Mexico, Uruguay and Canada. China exports a negligible amount of meat to the United States.

"The consumer, upon seeing the U.S.D.A. label, would naturally presume that it's a U.S. product," said Bill Bullard, chief executive of the Ranchers-Cattlemen Action Legal fund, United Stockgrowers of America, an organization of cattle ranchers better known as R-Calf. He said the effect for meatpackers was that "they are able to bring in a cheaper product and sell it under the reputation of the U.S. cattle industry."

Opponents of origin labeling say the measure is simply protectionism, aided by false claims about imported products. American meatpackers may stop buying imported cattle altogether given the costs of segregating and keeping track of such products.

They also say it would be difficult and expensive to label ground meat like hamburger, since it often includes meat from different cows.

"They talk about how the quality is better in the United States," said Mark D. Dopp, senior vice president for regulator affairs and general counsel for the American Meat Institute, a trade group. "The standards are all the same. For these people to talk about how all this inferior product is coming in, it's just nonsense."

Legislation for origin labeling floundered until the 2002 Farm Bill was coming together, in part because of a strong push by Thomas A. Daschle, then the Senate majority leader, where support for the labeling law is strong. As a compromise, origin labeling was made voluntary for the first two years before becoming mandatory in 2004.

But those efforts were quickly undone by the meat lobby.

Just after the law was passed, the secretary of agriculture at the time, Ann M. Veneman, called it "unfortunate" and suggested that origin labeling could violate trade agreements, drawing a strong rebuke from the law's advocates in Congress.

During Ms. Veneman's tenure, the top ranks of the Department of Agriculture included executives with ties to the meatpacking industry. For instance, her chief of staff, Dale Moore, was the former head of legislative affairs for the National Cattlemen's Beef Association. The same trade group employed her director of communications, Alisa Harrison, and the deputy under secretary, Charles Lambert, who would have overseen the origin labeling program.

The National Cattlemen's Beef Association, which represents both ranchers and meatpackers, opposes origin labeling.

The Department of Agriculture estimated that the cost of paperwork to manage the program in its first year would be $1.9 billion, a figure the Government Accountability Office said was questionable and not supported by the agency's records.

But the real undoing of origin labeling occurred in Congress.

In 2003, a year before the labeling was supposed to go into effect, Mr. Bonilla pushed through a delay of mandatory origin labeling for another two years.

Two years later, again largely because of Mr. Bonilla's efforts, the House passed an appropriations bill that prohibited the Department of Agriculture from spending money to put into effect origin labeling until September 2007.

According to the Center for Responsive Politics, a nonpartisan group that tracks campaign spending, Mr. Bonilla received $158,328 in campaign funds in 2006 from the livestock industry, making him the top recipient in Congress. He was also the top recipient of campaign funds from the livestock industry in 2004, with $132,900, and ranked second in 2002, with $78,350.

Mr. Bonilla, who was defeated in 2006 by Ciro Rodriguez, said it was common for committee chairmen to receive contributions from the industries that they oversee. Besides, he said his Congressional district was a huge cattle ranching and agricultural region.

Mr. Bonilla does not dispute that he delayed the labeling law from taking effect. But he said it was a bad idea that would be costly to not only cattle producers and meatpackers but grocery stores as well.

But now, with Democrats in charge of Congress, advocates of the labeling law are trying to mount their own lobbying and public relations blitz on Capitol Hill. And for now, they are receiving a warmer welcome from some Congressional leaders.

For instance, Mr. Bonilla's successor on the subcommittee, Representative Rosa L. DeLauro, Democrat of Connecticut, is a supporter of the labeling law. Ms. DeLauro received $100,750 in campaign contributions from agribusiness in her 2006 campaign, $4,000 of which came from the livestock industry.

"There will be mandatory COOL by 2008 at the latest," she said.

Copyright 2007 The New York Times Company