Negotiators seeking an end to Chicago's teachers strike sound more hopeful than they have in weeks, announcing they have achieved a "framework" that could bring students back to the classroom by Monday.

But the leader of the teachers union cautions against assuming the nearly weeklong walkout is over until her members have seen the final offer in writing in a meeting scheduled for Sunday.

"They are suspicious, you have to understand," Karen Lewis told reporters after a meeting with nearly 800 members of the union's House of Delegates. "We have been a little burnt by the (school) board in the past."

With no contract ready and the strike still formally in effect after days of anticipation over a deal to end it, a rally scheduled for Saturday was unlikely to be a victory celebration. Instead, it was shaping up as a show of force for organized labor after a string of setbacks, with participants coming from Wisconsin, Minnesota and perhaps as far away as Boston.