Saying American jobs were at stake, union leaders yesterday launched an all-out attack on a market-opening agreement with China, pledging a lobbying campaign to convince Congress to block it.

John J. Sweeney, president of the 13 million-member AFL-CIO, said the federation will "wage a full and vigorous campaign" against the trade deal, which paves the way for China to join the World Trade Organization. "We'll spend as much money as necessary," Sweeney said.

Stephen Yokich, president of the United Auto Workers union, sent a letter to President Clinton vowing to mobilize all of its members and the general public against a trade accord that he said was "contrary to the interest of working families."

But labor leaders conceded that they would not be able to match the business lobby dollar for dollar. Business has a lot riding on the agreement, which would open the vast Chinese market, potentially the world's largest, with 1.2 billion consumers.

Union leaders are worried that low-priced Chinese-made goods would flood the U.S. market, costing Americans their jobs, and that U.S. companies would take advantage of low-wage Chinese workers under the terms of the WTO agreement.

Union officials said their campaign will begin in earnest with marches and rallies at WTO meetings in Seattle from Nov. 30 to Dec. 3, and intensify next year before Congress takes up the trade agreement.

Analysts said labor's opposition to the China deal could hurt Vice President Gore, who is running for the Democratic presidential nomination and counting on union support in next year's election. The AFL-CIO and other unions have endorsed the Gore campaign, but labor leaders said the administration's position on China could erode rank-and-file support.

The trade agreement, which was announced Monday in Beijing, calls for China to slash tariffs and open a wide range of markets, and paves the way for Beijing to join the WTO after 13 years of negotiations.

In return for China rolling back its trade barriers, Clinton will have to persuade the Republican-controlled Congress to grant Beijing favorable access to U.S. markets in the form of permanent normal trade relations status.

That status would guarantee Chinese goods the same low-tariff access to U.S. markets as products from nearly every other nation. Without it, U.S. businesses could not benefit from China's commitment to roll back tariffs and other trade barriers.

"We will oppose the admission of any nation to the WTO until it is in compliance with core workers' rights," Sweeney told the National Press Club in Washington. "Supported by the vast majority of Americans, we will build a majority in Congress to sustain our position."

Many Republicans want Clinton to address their concerns about alleged Chinese espionage at U.S. nuclear labs, and have pressed the White House to increase security for Taiwan. Democrats in Congress want a commitment from Beijing to improve human rights and labor standards. Members of both parties are concerned about a growing trade deficit with China, the largest on record with any country.

CAPTION: John J. Sweeney says unions will wage a "vigorous campaign."