John J. Sweeney, the A.F.L.-C.I.O.'s president, said yesterday that he had already urged Democratic leaders in Congress to defeat Ms. Chavez. On Tuesday, several union leaders said, the labor federation's 54-member executive council will officially announce its opposition to the confirmation of Ms. Chavez, a conservative columnist and former Reagan administration official.

"She has spent the past 20 years opposing just about every important program, from the minimum wage to affirmative action to so many things important to working families," Mr. Sweeney said in a telephone interview. "It is very difficult to think of working with someone who is opposed to some of our basic labor laws, yet says she's going to enforce those laws. She's just not the right person to be secretary of labor."

Union leaders acknowledged that they faced an uphill battle in trying to stop the confirmation, but they said it was important to fight against someone they view as hostile to unions and unenthusiastic about enforcing workers' rights.

Several union leaders said they hoped they could block the nomination by winning the support of all the Democrats in the Senate, which is divided 50-50, and a handful of labor-friendly Republicans. The unions' determination to defeat Ms. Chavez was first reported yesterday by The Washington Post.

"I think the American labor movement has a responsibility to oppose her, to point out to the American people and to the United States Senate what kind of individual would be put in charge of the issues affecting working families in America," said Gerald McEntee, president of the American Federation of State, County and Municipal Employees and chairman of the A.F.L.-C.I.O.'s political committee.

Tucker Eskew, a spokesman for Mr. Bush, voiced confidence that Ms. Chavez would win Senate confirmation, despite labor's opposition.

"As secretary, upon confirmation, she will strongly enforce the laws of the land and strongly enforce the laws that look out for working Americans," Mr. Eskew said. "She comes form a working-class background. She has a record of promoting the interests of working Americans and she will do so as labor secretary."

To drum up opposition to Ms. Chavez, the A.F.L.-C.I.O. is distributing copies of her writings, which, union leaders say, often take a contemptuous or extreme stance on basic workers rights.

In her columns, Ms. Chavez has ridiculed sexual harassment lawsuits as being brought by "crybabies," has argued against the notion that women face a glass ceiling thwarting promotion into the senior ranks of business, and has likened supporters of an increased minimum wage to Marxists. She has condemned proposals to raise the federal minimum wage, saying such a step would reduce jobs and force many companies out of business.

Ms. Chavez, who was staff director of the United States Civil Rights Commission under President Ronald Reagan, is president of the Center for Equal Opportunity, a Washington research group. The center, a fervent opponent of affirmative action, says it is devoted "to the promotion of color-blind equal opportunity."

Labor union and civil rights groups have voiced concerns that Ms. Chavez may not enforce federal rules that require thousands of federal contractors to use affirmative action criteria.

Ms. Eskew said: "She will strongly enforce the civil rights laws of the nation, while increasing equal employment opportunities, including for workers under federal contracts. She has a history of supporting the tenets of what the president-elect calls affirmative access, an aggressive effort to reach out to Americans of all backgrounds, without establishing quotas or racial preferences."

After her selection was announced last week, Ms. Chavez sought to reassure workers, promising to promote safety on the job and to enforce the nation's labor laws. After noting that her father was a house painter and that her mother stood for long hours working in department stores and restaurants, she said, "I intend to keep faith with the men and the women who still work at jobs like those my parents held."

Still, labor leaders, who played a major role in Vice President Al Gore's campaign, often describe Ms. Chavez as antiunion. Although she worked as a lobbyist for the American Federation of Teachers two decades ago, she has written that teachers unions are often bad for the nation's schools. She has also condemned various strikes as being bad for the economy and has written that the idea of doctors' forming labor unions "ought to strike fear in the heart of every American."

Defending Ms. Chavez's writings, Mr. Eskew said that as a columnist, she was expected to be provocative. "We'd like the opponents to be reminded of the difference between a newspaper columnist and a cabinet secretary," he said. "The words of a columnist don't necessarily predict the works of a cabinet secretary."