- The teachers' bargaining team will share details about proposed contract language
- The union says the earliest teachers could return to their schools is Monday
- "However, no decision has been made to do so," the teachers' union says
- Supporters of the Chicago Teachers Union rally Saturday for a sixth day
Chicago (CNN) -- Chicago teachers will decide Sunday whether to end a strike that has paralyzed the nation's third-largest public school system and left hundreds of thousands of students out of class for a week.
Representatives from the teachers' bargaining team plan to share details about proposed contract language during a meeting in the afternoon.
"The earliest teachers and other school personnel could return to their schools could be Monday; however, no decision has been made to do so," the teachers' union said in a statement. "Delegates, the elected leaders of their schools, have the authority to suspend or lengthen the strike. They could also ask for at least 24-hours to talk to individual members in their schools before making a decision on what to do next."
Supporters of the Chicago Teachers Union rallied Saturday for a sixth day of a strike, which has shut down the city's schools even as a deal with the school board was in the works. Parents and students joined the strike Saturday to show solidarity.
"I am willing to stand by my teachers' side for as long as it takes," high school student Angela Casa told the crowd. "Through this whole journey, they are keeping their heads up for us."
Both sides expressed optimism that students could return to school Monday, but made it clear that a deal has not been made.
"We don't have an agreement, we have a framework for an agreement," union President Karen Lewis said.
The 29,000-member union and the city's school board reached a tentative agreement Friday over a dispute on new contract terms that had closed public schools for up to 400,000 students.
Union officials were meeting over the weekend to draft specific language for the agreement, Lewis said. They will present the document to a special committee of union representatives and a majority vote will be taken on whether to end the strike.
Chicago School Board President David Vitale remained optimistic.
"We have in place frameworks around all of the major issues that should allow us to conclude this process and to conclude it in time for our kids to be back in school on Monday morning," he said.
A source close to the negotiations said some of the terms include: keeping the current length of school year and school day; giving principals the freedom to hire their own teachers; and chief among the dispute's sticking points, updating the teacher evaluation system for the first time in 40 years.
Teachers were concerned about job security in the wake of a new program that evaluates them based on their students' standardized test scores. Union board member Jay Rehak called the program "data-driven madness."
As many as 6,000 teachers could lose their jobs under the evaluation system, said Lewis, who had called the system "unacceptable." The mayor's office, the city and school officials have questioned that job-loss figure.
The median base salary for teachers in the Chicago public schools in 2011 was $67,974, according to the system's annual financial report.
Chicago Mayor Rahm Emanuel praised the progress made between the two sides after days of sometimes contentious meetings.
CNN's Katherine Wojtecki and Sarah Aarthun contributed to this report.