By STEVEN GREENHOUSE
The presidents of 12 of the nation's largest labor unions called Wednesday for reuniting the American labor movement, which split apart three and a half years ago when seven unions left the A.F.L.-C.I.O. and formed a rival federation.
The union presidents issued their joint call after the transition team for President-elect Barack Obama signaled that it would prefer dealing with a united movement, rather than a fractured one that often had two competing voices.
David E. Bonior, a member of Mr. Obama's economic transition team who withdrew from consideration as labor secretary, helped arrange and oversee a meeting of the union presidents on Wednesday in Washington. The leaders are hoping, by April 15, to approve a plan to reunify, one union official said. But some officials said they might fail to reach agreement.
Mr. Bonior, a former House majority whip, said he would organize meetings with labor leaders over the next few weeks in the hope of hammering out details about what form a reunified labor federation would take.
The 12 union presidents issued a statement, saying: "The goal of the meeting is to create a unified labor movement that can speak and act nationally on the critical issues facing working Americans. While we represent the largest labor unions, we recognize that unity requires broad participation. "
The call for reunification was something of an about-face for the presidents of the Service Employees International Union, the Teamsters and several other unions that quit the A.F.L.-C.I.O. , asserting that the federation was stodgy and had not done enough to reverse organized labor's long decline. The breakaway unions formed a federation called Change to Win.
"There was a real sense of commitment to unifying our movement again," Randi Weingarten, president of the American Federation of Teachers, said Wednesday. "It was clear that many of us felt that the whole is greater than the sum of its parts, and we really want to do things to help American workers get their rightful place in society."
To bring about reunification, several labor leaders have called for revamping and modernizing the A.F.L.-C.I.O. , traditionally the nation's main federation, currently with 56 member unions. But several labor leaders have called for replacing the A.F.L.-C.I.O. with a new, more dynamic group.
There was general agreement that any future federation should focus on political and legislative matters, while also serving to encourage individual unions to do more to organize workers.
The leaders of several breakaway unions have called for changing the name of the A.F.L.-C.I.O. because they had vowed never to return to the same federation.
But many A.F.L.-C.I.O. officials argue that it would be silly to alter the name of such a well-known organization and replace it with a name that few Americans are familiar with.
Labor officials said they did not discuss on Wednesday who would succeed John J. Sweeney, 74, who is scheduled to step down this year after heading the A.F.L.-C.I.O. for 13 years.
Richard Trumka, the federation's secretary-treasurer and former president of the United Mine Workers, has been lobbying among union presidents to succeed Mr. Sweeney. But some union leaders, especially those in the rival labor federation, say they want a fresh voice leading organized labor.
The reorganizing proposals that unions president have floated in recent days include a rotating presidency for the A.F.L.-C.I.O. or its successor federation, with the presidents of individual unions serving two-year terms as head of the parent federation.
One A.F.L.-C.I.O. official described that plan this way: "The dukes want to replace the king."
But many officials oppose a rotating presidency, saying the parent federation needs a strong, visible president who, by dint of serving for several years, is recognized by Congress and the news media as the undisputed voice for labor.
Several presidents have also called for creating a strong executive director's position, partly in the hope that the parent federation would have two strong voices rather than one.
Those at Wednesday's meeting included Andy Stern, president of the Service Employees union, who led the walkout in 2005; as well as the presidents of the Teamsters, the United Steelworkers, United Auto Workers, and the American Federation of State, County and Municipal Employees.
One somewhat surprising attendee was Dennis Van Roekel, president of the National Education Association, which, with 3.2 million members, is the nation's largest labor union, but has traditionally remained outside any larger labor federations.
Officials from several Change to Win unions have said in recent months that they were seeing little advantage in maintaining a separate labor federation.