Among 114 product categories, U.S.-based producers boosted their domestic market share in only three categories between 1997 and 2005: heavy trucks and chassis, computer storage devices, and computer chips. Imports gained market share in 111 categories.

The survey from the U.S. Business and Industry Council, a nonprofit group in Washington of small and midsize manufacturers and a critic of U.S. trade policy, used Census Bureau data. The survey excluded inexpensive consumer products found in Wal-Marts, Targets and dollar stores. Toys, clothing, sporting goods and other products in those retail stores are typically blamed for the soaring trade deficit.

Instead, the study focused on industrial and engineered products, such as wireless equipment, plumbing fixtures, tire cord, navigation and guidance systems, power boilers, and heat exchangers.

Alan Tonelson, a research fellow at the council and author of the study, said yesterday that the study showed that the United States "is failing to pass the test of global competition." He said the country appeared to no longer be a place where many manufacturers want to invest in advanced factories.

A spokesman for the National Association of Manufacturers, the main trade group for manufacturing companies, said yesterday that there was a "mixed picture" for U.S. manufacturers and dismissed Tonelson's study as too pessimistic. "Manufacturing is still the heart and soul of the U.S. economy," spokesman Hank Cox said. U.S. manufacturers are losing market share, but the entire market is growing, allowing them to expand, Cox said.

"To be sure, U.S. manufacturing companies have a lot of problems," Cox said. "But to have Alan Tonelson and Lou Dobbs running around waving a bloody shirt, saying 'we've been sold down the river' does not help." Dobbs, a CNN commentator, has criticized U.S. trade policy.

The last recession pounded the manufacturing sector, causing it to shed about three million jobs. Profits at U.S. manufacturing companies have rebounded modestly in recent years. But job losses from earlier in the decade appear permanent, as factory employment has remained stuck at 14.3 million to 14.4 million since mid-2003.

"The reality is that until there is a change in the trade situation, there won't be new manufacturing jobs," said Daniel Meckstroth, chief economist with the Manufacturers Alliance, a nonprofit educational and business-research organization. The group is free-trade-oriented.

Meckstroth said the number of U.S. factories declined every year between 1997 and 2005, falling to 334,700 from 374,600. Meckstroth said he expected the factory level to stabilize this year. He said the nation's trade deficit as a share of the economy, now at about 6 percent, is unsustainable.

Many economists have said a weaker dollar might help manufacturing companies. But Tonelson said he believed import penetration rates would keep rising even when the U.S. dollar was weak. "Anyone who thinks that a major U.S. devaluation will be a cure-all for U.S. manufacturing is really kidding themselves," he said.

Tonelson also said it was unlikely that U.S.-made products were capturing a higher share of foreign markets, which would offset losses at home.

"It does not make sense to suppose that U.S. products are doing better in foreign markets than in their home U.S. market," Tonelson said.