WASHINGTON – Leaders of five dissident unions convened here yesterday to start a new labor federation that could ultimately rival or replace the existing AFL-CIO, but the dissenters remained beset by differences over whether to attempt to reform the old federation or abandon it altogether.

The unions that announced a new partnership yesterday – the Laborers, the Teamsters, the Service Employees International Union, Unite-Here, and the United Food and Commercial Workers – represent about 5 million workers. After a meeting at the Laborers headquarters, just across the street from the AFL-CIO, the dissident union chiefs blasted the federation and promised that the new “Change to Win” coalition would do a better job of organizing workers.

“We believe that this labor movement needs to be born again,” said Bruce Raynor, president of the hotel, restaurant, and laundry-workers union, Unite-Here. “The labor movement as personified by the current AFL-CIO structure has been one that has been unsuccessful in standing up for working families,” he said.

“Without a radical change, we cannot continue to survive as a significant force,” the president of the Laborers, Terence O’Sullivan, said. “This is not a fight among unions. It is a fight for justice for working people. In that fight, we cannot be content with continued failure.”

In a written statement, the president of the AFL-CIO, John Sweeney, warned that the new coalition could disrupt efforts to get labor back on track. “Workers are under the biggest assault in 80 years – now more than ever we need a united labor movement,” he said. “Now is the time to use our unity to build real worker power, not create a real divide that serves the corporations and the anti-worker politicians … Disunity only plays into the hands of workers’ worst enemies.”

The percentage of American workers who are union members has declined precipitously in recent years, in part due to the loss of manufacturing jobs to lower-wage countries. According to federal statistics, less than 13% of the workforce now belongs to a union. In the private sector, the number of union-affiliated workers is about 9%.

The perception that the AFL-CIO was doing little to reverse that trend caused a revolt in the ranks and nearly cost Mr. Sweeney his job. At a federation meeting earlier this year, several unions floated plans to downsize the federation sharply and to return back to the unions for organizing efforts 50% of the per member dues unions currently send to the federation.

Mr. Sweeney, who faces re-election at a convention in Chicago next month, produced a less radical proposal and ultimately beat back the dissenting unions. Several of the dissenting unions have made clear they would like to unseat Mr. Sweeney, but he now appears to have enough support to win another term.

While stymied inside the federation, the upstart unions have not relented in their criticism of the AFL-CIO or its leader. The Service Employees and Unite-Here have engaged in public discussions about withdrawing from the federation if their demands for changes are not met. Yesterday, the leaders of the Teamsters and the United Food and Commercial Workers said they are considering taking the same step.

“At our next executive board meeting, we’re going to be bringing this issue up to empower us to withdraw from the AFL-CIO if we see fit,” said James Hoffa Jr., the Teamsters president. “We have not made that decision yet.”

The president of the supermarket workers union, Joseph Hansen, said his union’s board met yesterday and authorized “disaffiliation” with the federation if it is deemed necessary.

Mr. O’Sullivan of the Laborers was mum about whether his union was considering such a move.

Mr. Hansen exposed a rift with some of the other unions when he indicated that he would mount a floor fight over the reform proposals during the Chicago convention in July. “We’re going to go to the convention. We’re going to fight like hell for our principles,” he said. “We will have a determined effort.”

The president of the Service Employees, Andrew Stern, said he was not sure whether such a battle would be productive because of convention rules that could make it difficult for the coalition’s proposals to pass.

Some of Mr. Sweeney’s allies have suggested that Service Employees, who have been the most vocal about quitting the federation, might not be seated at the Chicago convention because the union has been slow to pay its dues to the AFL-CIO. However, federation rules appear to allow Service Employees’ delegates to vote as long as the dues are paid before the convention opens on July 25.

One of the central arguments of the new coalition is that the AFL-CIO has focused on politics at the expense of grassroots campaigns to sign up new union members. “We don’t think throwing more money into a political process and ignoring organizing is going to get the job done. We have a sense of urgency,” Mr. Hansen said. “That can’t wait until the 2006-2008 elections.”

Mr. Hoffa said the current federation leadership sees politics as a cure-all for the movement’s ills. “The last election was not lost because of money. It was lost for other reasons,” he said. “Their idea is simply throw money at politics and that’s going to take care of everything. We reject that idea.”

The AFL-CIO chief, Mr. Sweeney, contends that the federation intends to redouble its organizing efforts. He has suggested that organizing would become even more difficult if labor abandons its political efforts.

While the unrest in the labor movement has been brewing for months, if not years, yesterday’s announcement appeared to be a watershed in terms of press attention to the issue. The event drew six television crews and more than two dozen reporters and photographers. Several dozen more listened in by phone.

A series of fiery, often profane speeches by the same dissident union chiefs in Las Vegas last month drew only a single reporter. The presentations to the national press corps yesterday were genteel by comparison.

While the dissidents are calling for a new and urgent emphasis on organizing, several of their unions have also lost members in recent years. A criticism that has been leveled at the dissenters’ coalition is that it is not racially diverse. Most of the unions joining the new coalition have substantial minority membership, but all of the presidents of those unions are white men.

Mr. Hansen said the coalition’s proposals to streamline the AFL-CIO would not undermine the federation’s commitment to diversity. He said a new 15-member executive committee would include four “diversity seats” set aside for minorities and women. The current executive committee has 24 members.