From Kyung Lah and Greg Botelho, CNN

Chicago (CNN) - Chicago school kids won't be back in class until at least Wednesday after teachers union representatives decided not to end a week-long walkout - despite a tentative contract deal reached by union leaders and school officials.

The move left Mayor Rahm Emanuel vowing to go to court to force teachers back to work, calling Sunday's actions by the union "a delay of choice that is wrong for our children."

The mayor announced in a statement that he's asked city lawyers to file an injunction in circuit court to "immediately end this strike."

CNN's Kyung Lah reported from Chicago; Greg Botelho from Atlanta. CNN's Ed Payne and Chris Welch also contributed to this report.