The current dispute between the Postal Service and unions representing nearly 600,000 of its workers is the latest act in a long-running power play.

The plot is more complicated than a struggle over wages and benefits, although that element is important.

At issue is whether the federal governmenmt can live with the kind of collective bargaining rights, including the right to strike, afforded workers in the private sector. That question also is central to the dispute between the Federal Aviation Administration and members of the Professional Air Traffic Controllers Organization, who seem determined to reject a tentative contract worked out on June 22 with the FAA.

Federal workers were given minimal bargaining right in January, 1962, with the signing of Executive Order 10988. Eight years later, Congress approved the Postal Reorganization Act, establishing the Postal Service as an independent federal agency and giving its workers bargaining rights similar to those enjoyed in the private sector, excluding the right to strike.

As a result of their new privileges, including the rights to negotiate grievance procedures and working conditions, as well as pay and benefits, postal service employe wages have increased faster than those of federal general service workers in the last 11 years, according to a USPS study whose findings largely are supported by other research.

For example, the pay for a federal worker at GS5, Step 4, increased by $6,291, 87.4 percent, since 1970, compared to a 173.5 percent pay increase -- up $12,492 -- for a Postal Service employe in the same grade.

The Postal Service argues that its work force, which is nearly 90 percent unionized, earns more than comparable workers in every sector of the private economy except mining. The average Postal Service salary, excluding benefits, is $21,146.

The Postal Service pay gains were the product of power wielded at the bargaining table by unions, especially the larger American Postal Workers Union (APWU) and the National Association of Letter Carriers (NALC). Though the leaders of those two unions have said they do not want a walkout, they concede that the right to strike, an action postal workers have taken illegally on two previous occasions, would enhance their bargaining power.

Postal management is under congressional mandate to make their deficit-prone operation self-sufficient by 1985. The Postal Service was $306.4 million in the red last year. To put it in the black, management must trim labor costs and become more competitive with the growing numbers of highly automated private providers of mail and other information services.

Accordingly, Postmaster General William F. Bolger has taken a hard line that has permeated every phase of the current negotiations.

Bolger initiated a futile legal action before the National Labor Relations Board aimed at determining the "appropriate" bargaining structure under which negotiations could take place. That action delayed the start of contract talks by seven weeks and made Bolger a target of union and some congressional criticism.

Postal Service representatives finally came to the bargaining table June 16. But, from the union's viewpoint, they brought nothing of substance. jThe unions were seeking a 41.3 percent to 50 percent wage and benefit increase over the next three years. The Postal Service, with a contract deadline approaching at midnight tonight, was offering a three-year wage freeze.

Bolger also took a hard line on the matter of possible new attempts to test federal antistrike statutes. Postal pay envelopes recently contained warnings that strikers were subject to dismissal, and Bolger obtained a Justice Department ruling that any postal worker who goes on strike can also go to jail on felony charges.

But APWU President Morris (Moe) Biller and NALC President Vincent R. Sombrotto, who were elected heads of their unions, on pledges to be tougher than their predecessors in dealing with the Postal Service, say they can't go home with what Biller calls an agreement "our members will tear up." But they also say they can't call for a walkout unless they feel it has a reasonable chance of being successful.

So, the two union leaders have been publicly talking tough and privately seeking accommodation, all with the hope of coming out with a repectable contract and avoiding a strike -- the kind of showdown that, if successful, could make their unions stronger, but also risks breaking them under the weight of federal penalties.