After years of often bitter rivalry, the American Federation of Teachers has raised the possibility of a merger with the National Education Association, a move that would create the largest union in U.S. history.

AFT President Albert Shanker discussed the idea in his keynote address to the federation's convention in Boston Monday. After outlining a new era of cooperation between the teachers' organizations, Shanker said, "I hope that when we meet two years from now, there is a positive report about. . . a bunch of things that we've done that will bring us closer together."

"For a long time," Shanker told delegates from the 744,000-member union, "we have worked for the idea that there ought to be one united teachers' union in this country." Shanker said that in the last year relations between the two organizations have become "significantly better." He cautioned, however, that "this is not an indication there's a piece of paper in my pocket we're about to sign."

In a brief statement issued from the NEA's simultaneous convention in Kansas City yesterday, NEA President Keith Geiger did not reject the merger notion as he and previous NEA leaders have.

"The National Education Association will continue its working relationship with the American Federation of Teachers on issues critical to education. I have established an ongoing dialogue with Mr. Shanker and we have agreed to work together on significant educational issues facing our nation," Geiger said. "However, at this time I do not anticipate any formal merger discussions between the two organizations."

Shanker, a onetime firebrand satirized as a madman in Woody Allen's movie "Sleeper," has been moving his union closer to the NEA, joining it to lobby at the federal, state and local levels against cuts in education budgets and for education reforms.

Relationships between the two unions have improved dramatically since Geiger's election a year ago. Geiger had strong ties with organized labor in his home state of Michigan and has been willing to operate the 2-million-member NEA more like a traditional trade union, in contrast to his predecessor, Mary Futrell, who ran the NEA as the professional association it had always been.

The NEA has been recruiting non-professionals from school support staff -- janitors, clerical workers, teaching aides -- to build its power in contract negotiations, and as a result has begun to act less like a professional society.