IN A FIERY speech before the AFL-CIO's constitutional convention in New York this week, federation chief Lane Kirkland widened the distance between organized labor and the Reagan administration. Even as the delegates applauded, however, the administration was making new overtures to the labor movement. President Reagan directed the heads of federal departments and agencies to consult with labor on policy matters and invited labor leaders to meet with him next month.

This leaves the AFL-CIO's leaders with a tricky choice. Should they continue the federation's drift toward closer alignment with the Democratic Party, or begin to do serious business with the party in power?

Organized labor has found new unity in recent months in its opposition to the Reagan economic and social policies. Solidarity Day was a big success for Lane Kirkland's efforts to make the labor movement a more aggressive and potent force on the political scene. You can't take to the streets very often, however, and keeping the spirit of protest alive may require something that neither labor nor the Democratic Party currently has--a platform that responds to the changing needs and attitudes of the rank and file.

A substantial minority of union members voted a year ago for Ronald Reagan. Among those workers that organized labor might hope to recruit in the future, Republican support--or at least conservative leanings--may well be still stronger. Perhaps some of those workers have changed their minds since last November as the details of the president's program became clearer. Nonetheless, the feeling that the old policies weren't working was a real one, and it needs attention.

This is not to say that every element of discontent among labor's ranks deserves consideration. The labor movement has rightfully prided itself on leading its membership in some directions--notably toward civil rights and social welfare concerns--that the membership itself might otherwise have been reluctant to go in. Union members, however, are much better educated and more sophisticated than they were a generation ago. They want different things from their jobs, and they are more aware of the real limits placed on their demands by a stagnating economy, shifts in the structure of industry and international competition.

As labor's leaders come down to the specifics of how to address those concerns and generally advance labor's cause on the political scene, they are likely to realize that they will need some help from the federal government--even if Ronald Reagan happens to be running it. Many issues important to labor are more a matter of good public policy than of partisan politics. Lane Kirkland recognized that two weeks ago when he called upon the federal government to help organized labor root out crime and corruption among its ranks. That was an important overture on labor's part that the administration and the AFL-CIO might well use as a basis for exploring the common ground that may exist between them.