The earliest SEPTA's largest union would strike would be this weekend, officials said.
"I can't promise anything beyond this week," said Willie Brown, president of Transport Workers Union Local 234, said Monday. "At the end of the week, after negotiating with SEPTA for the rest of the week, I will evaluate where we are and make that determination whether or not a strike will be necessary."
How far a part are the two sides?
"California and Pennsylvania," Brown said.
Will he give riders 24 hours notice?
"I guess I could do that," Brown said.
In a statement, SEPTA said it "is pleased that TWU 234 has agreed to provide our riders 24 hours notice if they decide to strike. We however hope we can continue bargaining."
The some 5,000 union members — which includes bus, train and trolley operators, mechanics and cashiers — have been working under an expired contract since March. The union last went on strike in 2009.
Brown re-iterated Monday that the union is mainly asking for pension reform and a short-term contract to hold members over until the Affordable Care Act takes effect in 2018.
"If SEPTA comes to the table with a serious offer, we can make this thing happen," Brown said.
In the statement , SEPTA said noted that "Throughout the country defined benefit pension plans are disappearing and being replaced by defined contribution plans, such as 401(k) plans."
"Nevertheless," the statement continued, "SEPTA continues to provide reasonable wage, pension and health care benefits for all employees."