Today's vote isn't on the contract offer itself, but on whether to continue the strike.
The contract will still have to be submitted to a vote of the full union membership before it's formally ratified.
Some union delegates have been taking straw polls of rank-and-file teachers to measure support.
A teacher picketing outside an elementary school today says he "desperately" wants to get back to his students and their lab experiments.
Heath Davis says he's optimistic that today's vote could end the strike that has kept 350,000 students out of the classroom.
But he says there are still concerns about the academic calendar, pensions and resources for special education, in addition to the issues of teacher evaluations and recalls of laid-off teachers.
The striking teachers have started to feel pressure to decide quickly on the tentative contract that is described as a good deal for the union by labor and education experts, and even some union leaders.
The city went to court yesterday looking for an injunction to force the teachers back to work.
A judge has scheduled a hearing for tomorrow.
(Copyright 2012 by The Associated Press. All Rights Reserved.)