The Port Authority and the union representing bus-trolley workers will hold their first face-to-face meeting tomorrow to talk about a new labor agreement.

The meeting time and location have not been disclosed because management and officials of Local 85, Amalgamated Transit Union, have previously expressed intentions not to negotiate "in the media" and raise public speculation about what may become the most contentious period in the authority's 42-year history.

Attorney Bruce Campbell, of the Pittsburgh law firm Campbell, Durant & Beatty, will be chief negotiator for management, a role he has played many times in past dealings with Local 85.

Patrick McMahon, Local 85 president-business agent, will be chief negotiator for the union. Local 85's labor counsel is attorney Joseph J. Pass, of the Pittsburgh law firm Jubelirer, Pass & Intrieri, who also has represented the union in contract negotiations and other legal matters for several decades.

The current contract covering about 2,600 union operators, mechanics, maintenance workers and other hourly employees expires at midnight June 30.

If the two sides are unable to reach an agreement on a new pact by the deadline, they move to a fact-finding process and then to further negotiations in the presence of state, and possibly federal, mediators. Union officials have always considered a strike a measure of last resort; there hasn't been one since a 28-day walkout in 1992.

What's different this time is that Allegheny County Chief Executive Dan Onorato has threatened to withhold money that the Port Authority uses as its "local match" to draw down state funds unless management and the union institute reforms and cut liberal healthcare and early retirement benefits. Mr. Onorato has characterized the benefits as "outrageous."

Without a continuing flow of county money, about $27 million a year for the operating budget, the Port Authority may be unable to stay afloat. Its 2007-08 fiscal year ends on the same date as Local 85's contract.

The Pittsburgh Downtown Partnership has already notified its business members to start preparing contingency plans for a strike just in case.

Mr. McMahon, who's strongly supported by Local 85 retirees who have a voice in union elections, has vowed to oppose reducing benefits agreed to in the current and previous contracts.

He has pointed to the current contract in which union members gave up 1 percent of 3 percent annual pay raises to help offset the cost of health insurance for the first time. Retirees also have to pay 1 percent; new employees, 5 percent. A higher co-pay and some tighter requirements also were part of givebacks.

Mr. Onorato and Gov. Ed Rendell helped settle the last contract by joining a marathon bargaining session in November 2005, five months after the previous contract had expired.

Some of the contention was sparked last fall when the Pennsylvania Economy League released a study comparing benefits at the embattled transit agency with unionized transit workers in Philadelphia, and state and county government workers.

Its key findings maintained that the authority's average hourly union wage of $23.20 an hour, when adjusted for the cost of living in Allegheny County, was higher than another major metropolitan transit system in the nation.

The PEL also noted that the Philadelphia-based Southeastern Pennsylvania Transportation Authority is spending $7.3 million on retiree health care this year compared to $29.2 million at the Port Authority, which is three times smaller.