The union can inflict maximum pain, calling a strike just as the World Series and the national spotlight arrive in Philadelphia.

SEPTA, meanwhile, can claim real financial distress, as its costs rise, its ridership declines from recent record highs, and anticipated state subsidies are threatened.

In the middle, as usual, is the riding public.

Those who depend on SEPTA buses, subways and trolleys to get to work and school - never mind sports events - can do little but watch the labor struggle from the sidelines.

The union today said that its deadline for going on strike is 12:01 a.m. Sunday, but a strike could be called beforehand.

Gov. Rendell, who was instrumental in breaking an impasse to settle the last SEPTA strike in 2005, today said he "would, if asked, try to be helpful," said spokesman Gary Tuma. Rendell will be available, since he'll be in Philadelphia for the World Series.

U.S. Rep. Robert Brady (D., Pa.), a frequent mediator in local labor disputes and an architect of the 2005 SEPTA settlement, said "it's too soon" for him to get involved.

"As long as they're talking, they're fine," Brady said.

Mayor Nutter said there is "no acceptable reason there should be a strike."

He urged SEPTA and the union to "stay at the negotiating table and figure this out."

Game 3 of the World Series will be in South Philadelphia Saturday night, Game 4 Sunday night, and Game 5 (if necessary) on Monday night.

Nutter said a possible SEPTA strike amidst a nationally televised baseball series is just "one more additional component" to a hectic weekend on the national stage for Philadelphia.

In addition to World Series games, there's a Flyers game Saturday afternoon, a Pearl Jam concert the same night, and an Eagles game on Sunday.

A transit strike would affect not only sports fans and commuters, the mayor said.

"I'm also concerned about people being able to get to their doctor and hospital," he said.

Bargaining continued today at the Holiday Inn in Old City, with both SEPTA and Transport Workers Union Local 234 led by first-time chief negotiators (SEPTA chief labor officer Fran Keating and TWU president Willie Brown).

The two sides yesterday discussed for the first time the heart of the dispute: wages, benefits and pensions.

"We're getting there . . . slowly," said TWU spokesman Robert Wolper.

The union, which represents about 5,100 bus drivers, subway and trolley operators and mechanics, has been without a contract since early spring.

For the union, the threat of a strike during the World Series offers unanticipated leverage. SEPTA and the city would dearly like to avoid the spectacle of milling crowds trapped in South Philly after Saturday's game.

But SEPTA also has some leverage of its own: a worsening financial condition.

Passenger revenues are down about 5 percent from a year ago. Operating expenses were about $5.5 million higher through August than in the same period in 2008.

And some anticipated state subsidies for SEPTA may end next June if the state continues to be denied federal permission to impose tolls on Interstate 80.

Although SEPTA's budget this year includes a 3.5 percent increase for labor costs, the transit agency says none of that money is earmarked for new raises. It is needed for previously contracted wage increases, 93 additional employees on the payroll, and the labor costs of 65 new customer-service initiatives, said chief financial officer Rich Burnfield.

According to TWU officials, SEPTA management has proposed no wage increase for the first two years of a four-year contract and a 2 percent increase in each of the final two years. It also wants to increase worker contributions to health coverage from 1 percent to 4 percent and freeze the level of pension benefits.

The union wants a 4 percent raise in pay each year and health contributions to remain 1 percent. It is also seeking an increase in pension contributions from $75 to $100 for every year of service.

The TWU also is seeking changes in subcontracting and training provisions to allow members to do maintenance and repair work on buses and trolleys now done by outside contractors.

SEPTA bus, subway, and trolley operators earn from $14.54 to $24.24 an hour, reaching the top rate after four years. Mechanics earn $14.40 to $27.59 an hour.