Inside or outside the AFL-CIO, convincing workers that joining a union will make life better is a tough sell.

Increasingly hostile employers, a legal structure that is increasingly anti-union, globalization and fierce competition all threaten labor's organizing attempts.

"You put all that together, and it has threatened not just the survival of unions, but unions as a powerful and political force," said Harley Shaiken, a professor at the University of California at Berkeley who specializes in labor issues.

One of the strongest forces keeping unions from organizing workers is employers who are willing to play hardball to keep unions out, as Wal-Mart proved when it eliminated a store department after a few of its employees voted to join a union, and closed a Canadian store in another case rather than negotiate.

And some of the problems stem from the labor movement itself, which critics say has been slow to adjust to the changing economy.

It also has been a long time since the labor movement produced any larger-than-life leaders who appeal to the popular imagination. The last labor leader with anything resembling a nationwide following was Cesar Chavez of the United Farm Workers, who died in 1993. And now, after this week's splintering, labor movement leaders are openly trashing one another.

"They've had a thousand excuses why they can't organize over the last 30 years. They have not put enough money into it, enough focus or muscle into it," said Patrick J. Cleary, a spokesman for the National Association of Manufacturers. He also said labor was having trouble organizing because there is not as great a divide between workers and management as in the past. "Where there is a polarized workplace, they have a lot more success," Cleary said.

The departure from the AFL-CIO of the Service Employees International Union and the International Brotherhood of Teamsters comes after a decline in union membership from 33 percent of the workforce 50 years ago when the labor federation was born, to 12.5 percent. The defecting unions, two of the movement's largest and most powerful, said they are leaving because of the federation's failure to halt the decline.

Labor's downward slide has been exacerbated by legal rulings that have gone against organized labor, and by public perception that unions are ineffective, according to several labor experts.

Last year, the National Labor Relations Board overturned three major decisions, ruling that temporary workers will no longer be able to bargain for job benefits as part of a unit with permanent employees; that graduate teaching assistants at universities are not employees and therefore cannot organize; and that employees of nonunion companies are no longer entitled to have co-workers present when they are interviewed in disciplinary investigations.

The board "is a very aggressive board that . . . interprets the law in a way that is tipped toward employers," said Kate L. Bronfenbrenner, director of labor education research at Cornell University. "The board is clearly biased towards employers and is making decisions one after another that way."

But, Bronfenbrenner said, the tough climate for organizing goes beyond the NLRB. Employers are using the threat of plant closings to intimidate workers, she said. "Employers are emboldened under the current administration to break the law or act within the law to aggressively oppose unionization efforts through a combination of threats and intimidation."

The United Food and Commercial Workers Union, which is trying to unionize Wal-Mart's 1.2 million U.S. employees, has filed more than 370 unfair-labor complaints against the retailer since 1995 -- about 90 percent of the charges filed against the company, according to NLRB records.

"There are almost endless anecdotes of what has taken place on the job that has made it so difficult to join a union," Shaiken said. "It has become an abstract right that is usually and routinely violated on the ground. Certainly for most workers, fear makes their decision."

Workers poured into unions in the late 1930s after they won the right to organize under the National Labor Relations Act in 1935. In 1981, though, in a move that bolstered the willingness of companies to take on unions, President Ronald Reagan fired 12,000 unionized air-traffic controllers who were striking for higher pay. Today, just 8 percent of private-sector workers are union members.

Unions are attempting to figure out how to strengthen organizing efforts. The UFCW recently formed Wake Up Wal-Mart, a group that is holding rallies and conducting online campaigns against the company's labor practices, after the union found that attempting to organize the company store-by-store wasn't working.

The SEIU is trying to organize on a larger scale, rather than one company or one locality at a time. "You can't improve the lives of workers by just looking at one work site," said Stephen Lerner, director of SEIU's property services division, which represents, among others, janitors and building security guards. Last week, janitors throughout the country who work for cleaning services company ABM Industries Inc. decided to honor picket lines in other cities to support striking janitors who work for the company in Houston and Indianapolis. The janitors themselves adopted the decision to honor the picket line at the SEIU's convention almost two years ago.

But despite new efforts, traditional organizing drives are being met with more resistance than ever.

The American Federation of State, County and Municipal Employees (AFSCME), which has supported the current leadership of the AFL-CIO, is trying to organize about 9,000 employees of Resurrection Healthcare Corp., based in Illinois. Activist workers "are fired on trumped-up charges to send a signal that chills the organizing activity and chills people's willingness to step forward," said Jim Schmitz, AFSCME's director of organizing.

Wal-Mart has a handbook called the "Manager's Toolbox to Remaining Union Free." Marked confidential, the books include a phone number for managers to call if they believe workers are talking about organizing. The handbook includes questions and answers such as, "Can we terminate a salt [union activist] who works in our facility?" The answer is no, not based on their activism alone, followed by another question. "If we hire an applicant who is unproductive and also happens to be a salt [a union activist], can we terminate him/her?" The answer: "Yes, as long as the reason for termination is based on job performance and not his/her union affiliation. Be sure you have documentation to support the termination."

When a store is under threat of a movement to unionize, Wal-Mart also sometimes flies in executives on a corporate jet to stunt the effort. So far, it has worked. Not one of Wal-Mart's 3,500 U.S. stores is unionized.

Employees of a Wal-Mart tire shop in Loveland, Colo., tried to organize a union. They lost a representation election.