Contract talks between the U.S. Postal Service and unions representing nearly 600,000 postal workers will begin today, nearly two months late.

The very late start means that the talks -- which are expected to focus on pay, workplace safety and job protection -- could go beyond July 20, when Postal Service contracts with four national unions expire.

Like other federal workers, postal employes legally are forbidden to strike. Accordingly, union officials have sought to downplay strike talk in the media and among their members. But leaders of the two largest groups, the American Postal Workers Union and the National Association of Letter Cariers, have warned that the delay has "poisoned the atmosphere" in which negotiations will take place and has removed the presumption of "good-faith bargaining."

"'Confrontation' is the last word on our list," and NALC President Vincent R. Sombrotto in a recent meeting with New York letter carriers. "But it is a word that is there and that can be used if, unfortunately, it has to be used."

The negotiations -- the largest this year in terms of workers represented -- were delayed beyond the scheduled April 22 start because Postmaster General William F. Bogler unsuccessfully petitioned the National Labor Relations Board on April 17 to define the "appropriate" structure under which the talks could be conducted Bolger said the current arrangement involving four unions -- at least one of which bargains separately from the other three -- was "unworkable."

However, Bolger's arguments were rejected April 30 by acting NLRB Regional Director Louis J. D'Amico, whose decision was upheld last week by the full board.

The postmaster general contends that, even with the delay, "Time remains for the parties to settle all issues before the expiration date, and I believe we should be able to achieve settlement by then."

However, in a contract negotiations backround paper, Postal Service officials described in detail the legal consequences of a strike by their workers -- forfeiture of right to employment in the Postal Service or other federal agencies and loss of pay and benefits. The paper also reviewed actions taken against striking postal workers in 1978, when the current contract was negotiated.

Adding to the apparent acrimony surrounding the opening of the talks is an emotional side issue involving the proposed naming of a New Jersey-based postal facility after a worker who was killed there.

Rep. Frank J. Guarini (D-N.J.) has introduced leglislation proposing to change the name of the New York Bulk Mail Center at Jersey City, N.J., to the "Michael McDermott Bulk and Foreign Mail Center" in honor of McDermott, who was killed in a work-related accident at the center.

The proposal is popular among New York are postal employes, the largest and most militant group of organized postal workers. But Bolger opposes the idea, saying in part: "Generally, when postal facilities or federal buildings are designated with the name of a person, the purpose is to honor someone for distinguished achievements."