"We are not going to go on strike because the public deserves to have a riding system that works. We will give the (transit agency) one more day to get it together," said Antonette Bryant, leader of Amalgamated Transit Union Local 1555, one of the two unions in talks with BART.
BART officials said they presented the last best offer Sunday afternoon, and that the unions have two weeks to consider it before it's taken off the table.
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The unions said workers will walk off the job at midnight Monday if an offer isn't reached by then.
BART workers went on strike for nearly five days in July and were set to do so again Friday when a cooling-off period ordered by Gov. Jerry Brown ended, but they agreed to negotiate through the weekend.
Nearly 370,000 riders take BART every weekday, and its 104 miles of track make it the nation's fifth-largest commuter rail system.
