As several thousand U.S. Postal Service workers paraded toward Pennsylvania Avenue Wednesday, seeking attention for their current labor negotiations police dutifully stopped automobile traffic to permit marchers to cross the avenue.

And what top government official sat in the back of the first limousine stopped for the parade, totally unrecognized by the postal workers?

It was 37-year Post Office veteran William F. Bolger, the 64th successor to Benjamin Franklin as Postmaster General of the United States.

Many of the demonstraters were from the northeastern states and were recognized by Bolger, a legacy of his days as regional postmaster general in the northeast. He became deputy to former Postmaster General Benjamin Bailar in 1975 and then the chief Postal Service 's executive, after Bailar resigned last February.

It was appropriate that the workers didn't notice Bolger, for he has remained publicly aloof from the bargaining sessions with several labor unions that began here April 20 and now are big conducted on a daily basis at a motel near the Postal Service's headquarters in L'Enfant Plaza.

Some union leaders and members have threatened what would amount to an illegal strike if new contracts have not been negotiated to replace those that expire at midnight next Thursday covering 570,000 workers. The postal management made its first wage package offer yesterday and the two sides were said to be "far apart".

Despite appearances, Bolgar is involved around-the-clock in evolving strategy for the labor talks. And the Postal Service, as well as private businesses here and in other cities, have contingency plans to move at least some mail if a regional or national walkout takes place.

But Bolger said in an interview that he expects a peaceful settlement to result in new contracts, a view he has stated many times since taking office.

And he is devoting much of his attention to other Postal Service problems so big that a controversy over wages for two years appears dwarfed in contrast.

The Postal Service's entire future has been called into question in the wake of continuing deficits, soaring mail rates that are chasing away large-volume business users, the potential of electronic communication stealing even more business in future decades, and legislation passed by the House that would make the Postal Service like the government department that it used to be, under more congressional and executive control.

Bolger said the Postal Service clearly is at a "turning point." In previous years, he said, too much management time has been devoted to operating the post office system "from the legal and economic standpoints, such as how to set rates."

In future months and years, postal management is going to be studying how competitive services can move mail and packages, with an eye toward developing and marketing services that meet specific customer demands, he asserted.

Indeed, Bolger said that if postal authorities decide they cannot provide a first-class mail service required by one particular class of customer - as an example he mentioned the real estate industry, which needs rapid delivery for its regular property listings, then private business should be permitted to make the attempt, a step that would end the historic Post Office first-class mail monopoly. Bolger said he thinks the monopoly requirement must be maintained for at least most first-class mail and emphasized his view that his management can develop new services required by various users.

Planning major policy shifts that will attempt to keep the Postal Service a viable operation is Bolger's top priority.

But labor also is a big factor in long-term planning, since wage and fringe benefit costs eat up 85 cents from every dollar of revenue. Bolger emphaized that a second phase of mechanization and automation in handling letters is about to begin - one that will allow the Postal Service to continue reducing its overall payroll.

Since the Post Office Department was abolished, postal employment has declined 10 percent to about 650,000 and mail volume has increased from under 90 billion pieces each year to an estimated 95 billion in the current fiscal year that ends Sept. 30, indicating a significant gain in productivity.

Although much attention is focused on the wages of postal workers - an average of $15,877 a year, up 87 percent since 1971 - a major confrontation in the labor negotiations is expected over job security. Included are unions goals of guaranteeing no layoffs altering transfer policies and dealing with overtime.

The postal negotiations have become a lightning rod in the Carter administration's attempts to control inflation. Barry Bosworth, director of the Council on Wage and Price Stability, said this week that if postal workers reach a large wage settlement that administration will "have to seriously rethink" the labor side of its voluntary campaign to whip inflation.

The unions have asked for pay increases and cost-of living boosts totaling about 14 percent during the first year of a proposed two-year contract. The administration wants the postal workers to accept a 5.5 percent ceiling on wage increases. Postal budget estimates for the coming year indicate plans for wage increases of about 6 percent.

When the old Post Office Department was reorganised in 1970-1971, congressional wage setting for postal workers was stopped and collective bargaining was started, removing Post Office workers from federal civil service pay requirements.

Assessing the talks to date, Bolger said: "I don't see a substantial amount of progress, but there is plenty of time left - eight days."

As chief federal meditator Wayne Horvitz met with representatives of postal management and unions, Bolger talked in his office atop L'Enfant Plaza.

Asked about union leaders' complaints that postal management had not even responded until yesterday with an initial economic offer to counter that of the unions, Bolger indicated that the delay might have been part of a larger strategy to allow the unions to attract attention to their demands. It would "not have been appropriate" to upstage the planned demonstration on Wednesday by unveiling a full proposed settlement before then, he said.

The Postmaster General insisted he hasn't had "any pressure from the administration whatsoever" on the wage talks, outside of public statements by White House officials or congressional testimony.

Bolger said he met with Carter about six weeks ago but emphasized the independent nature of the Postal Service and the absence of day-to-day relations with the executive branch.

Earlier this week, a White House aide testified before a Senate committee with general support for proposed legislation that would bring about far less change than that proposed by the House bill.

By a lopsided 384 to 11 vote on April 6, the House approved legislation again make the Postmaster General a presidential appointee, to give Congress veto power over such policy decisions as Saturday deliveries, to abolish the Postal Service's independent board of governors and to increase annual subsides from $980 million a year up to $1.7 billion.