Chicago Teachers Union President Karen Lewis says delegates have decided to extend their weeklong strike until at least Wednesday to give them time to consult with rank-and-file members before voting to suspend the walkout. Watch her news conference.

Updated at 10:25 a.m. ET: Delegates from the Chicago Teachers Union told their bargaining team Sunday that they want to meet with the schools they represent before making a decision about whether to end their strike.

"They’re not happy with the agreement and would like it to be a lot better for us than it is," Union President Karen Lewis said in a news briefing Sunday evening, adding that they are returning to their schools with the proposal because they do not want to feel rushed to make a decision.

That means Chicago public schools will remained closed Monday and likely Tuesday, affecting 350,000 kindergarten, elementary and high school students. Parents should plan for their children to be out of school until at least Wednesday, Lewis said.

Following the announcement, Chicago Mayor Rahm Emanuel, calling the strike "illegal," said he would file an injunction to force an end to the walkout.

"I will not stand by while the children of Chicago are played as pawns in an internal dispute within a union," Emanuel said, adding that the union walked out over issues that are not subject to a strike under Illinois state law.

The union delegates aren't scheduled to meet again until Tuesday, in part out of respect for for the Jewish holiday Rosh Hashanah, which began at sundown Sunday.

A union bargaining team and city officials had hammered out a proposed contract that would move away from merit pay and allow teachers to appeal their evaluations.

Sitthixay Ditthavong / AP Chicago Teachers Union delegates arrive for a meeting Sunday in which they are expected to review a proposed contract and vote whether to suspend the week-long strike.

A faction of the union sees it as a "back room deal" that does not have unified support. A source close to the union told NBC Chicago that Lewis' caucus shouted obscenities at her and other leaders late Saturday night, saying, "You sold out" and, "Rahm's getting everything they wanted, what the hell did we get?"

Lewis, exhausted from a tense week, indicated that she's done negotiating and asked "Will my own caucus defy me?"

At the heart of those who oppose this new deal - they feel the negotiating team did not fight for paraprofessionals and special education teachers and students.

Read full coverage at NBCChicago.com

Some delegates shouted at Lewis there is "no way to vote on something we haven't seen."

Teachers revolted last week against sweeping education reforms sought by Emanuel, especially evaluating teachers based on the standardized test scores of their students. They also fear a wave of neighborhood school closings that could result in mass teacher layoffs. They want a guarantee that laid-off teachers will be recalled for other jobs in the district.

"They're still not happy with the evaluations. They're not happy with the recall (provision)," Lewis said of delegates.

Still, Lewis seemed energized in a statement Saturday night, buoyed by the agreement, which came after a weeklong strike that began on Sept. 10.

"This union has proven the Chicago labor movement is neither dormant nor dead," Lewis said in a statement on the union’s blog late on Saturday. "We have solidified our political power and captured the imagination of the nation. No one will ever look upon a teacher and think of him or her as a passive, person to be bullied and walked on ever again."

Emanuel's chief negotiator, School Board President David Vitale, said the union should allow children to go back to school while the two sides complete the process.

"We are extremely disappointed that after 10 months of discussion reaching an honest and fair compromise that (the union) decided to continue their strike of choice and keep our children out of the classroom," Vitale said.

The contract includes what Lewis called victories for the 29,000 union members, which she outlined on the union’s website:

PAY: The teachers union wants a three-year contract that guarantees a 3-percent increase the first year and 2-percent increases for the second and third years. The contract also includes the possibility of being extended a fourth year with a 3-percent raise. A first-year teacher earns about $49,000, according to the National Council on Teacher Quality; the highest-paid teacher earns $92,227.

Chicago Public Schools would move away from merit pay for individual teachers.

EVALUATION: Teachers would be evaluated 70 percent in terms of how they teach (“teacher practice”) and 30 percent in terms of how their students improve (“student growth”). Evaluations will not affect tenured teachers during the first year, and teachers may appeal their evaluation.

HIRES: Responding to parent demands, Chicago Public Schools would hire more than 600 teachers specialized in art, music, physical education and foreign languages, among other teacher specialties. More than half of large school districts rehire laid-off teachers, according to The New York Times; the Chicago school board has pushed to leave control to principals.

Those new hires will allow for the longer class day – which will be seven hours for elementary school students, up from five hours and 45 minutes. Chicago had been known for one of the shortest school days in the country -- a point that became a sticking point for Mayor Rahm Emanuel.

Of those new hires, half must be union employees who were previously laid off. (Higher-rated teachers would have a better chance at being rehired, the Chicago Tribune reported.)

BULLYING: The contract demands ending bullying by principals and managerial personnel to “curtail some of the abusive practices that have run rampant in many neighborhood schools.” Principals, however, will continue to exercise power over hiring teachers, the Tribune reported.

In one instance, according to CBS Chicago, dozens of complaints were made about a principal at Josiah Pickard Elementary School during his five years on the job. A union representative told CBS Chicago that the volume of complaints was not normal for a principal.

TEXTBOOKS: Chicago students would have their textbooks on the first day of school instead of having to wait up to six weeks

Related: Chicago strike: Will teachers union approve proposed contract?

The strike may have hurt Mayor Rahm Emanuel’s image as a hard-nosed innovator, the Chicago Tribune reported, largely because of the mayor’s aggressive statements about teachers – which he implied after the school board nixed half their pay raise.

The strike received nationwide attention in part because Chicago is the third-largest school district in the nation and its teachers hadn’t gone on strike for 25 years, since 1987.

But the strike has made headlines also because Emanuel was Obama’s first chief of staff. Obama, whose daughters attended the private University of Chicago Laboratory School (known as the “Lab school”), campaigned on public school reform and has advocated merit pay.

On Friday, Emanuel released a more muted statement than his ones in the past, according to the Tribune:

"This tentative framework is an honest and principled compromise that is about who we all work for: our students. It preserves more time for learning in the classroom, provides more support for teachers to excel at their craft and gives principals the latitude and responsibility to build an environment in which our children can succeed."

Emanuel had argued for a long school day – which he appears to have achieved with the proposed contract. For high schools, the bell would ring after seven and a half hours.

The contract doesn’t end the school district’s woes, however. After school doors open again, the school district is likely to shutter schools to help close a projected $1 billion budget deficit for the 2014-1015 school year, according to the Tribune.

NBC's Isolde Raftery, Sevil Omer and Reuters contributed to this report.

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