Updated at 3:29 p.m. ET: CHICAGO -- Amid a dispute over pay and longer school days, Chicago teachers have voted to authorize a strike, the union said Monday.
Leaders of the Chicago Teachers Union, which represents 25,000 members, say the vote gives the union the legal authority to call a strike in the fall and provides "added leverage" in negotiations with the city.
"While the Union has made no determination on whether a strike will be needed, leaders say the authorization vote has now given them added leverage at the bargaining table," teachers union spokeswoman Stephanie Gadlin said in a statement.
Even with the authorization, a walkout couldn't happen until at least mid-August under a process laid out in Illinois law, according to The Chicago Tribune. Upwards of 400,000 students would be affected.
The vote not only exceeded the 75 percent required by state law, but some school networks voted 100 percent to authorize a strike, the union said.
"We're pleased," Gadlin told NBCChicago.com, but added: "We know there will be challenges by [Chicago Public Schools].
Officials with Chicago Public Schools have called the vote premature. Chicago Public Schools’ CEO Jean-Claude Brizard has questioned why the vote was held before the district has made its final offer and before the recommendation by an independent fact-finder.
“The Chicago Teachers Union leadership pushed their members to authorize a strike before giving them the opportunity to consider the independent fact finder’s compromise report due in July," Brizard said in a statement. "That's a shame. The CTU leadership left the teachers with a choice between a strike and nothing -- that's a false choice. As a former teacher, I am disappointed that union leadership would rush their members to vote for a strike before having the complete information on the table."
The strike authorization vote began Wednesday, and according to union officials, 91.55 percent of union members cast a ballot. The tallied votes give the union legal authority to call a strike in the fall.
Teachers and school officials are in contract negotiations but union leaders say they are far apart when it comes to teacher pay and how teachers will be compensated for longer school days.
Mayor Rahm Emanuel last year rescinded a four percent pay increase and pushed for a longer school day. CPS has since proposed a five-year contract which guarantees teachers a two percent raise in their first year and lengthens the school day by 10 percent.
Union officials are pushing for a two-year contract that would reduce class sizes and give teachers a 24 percent raise in their first year and a five percent raise the second year.
"This is a reflection of the treatment we as teachers have been subjected to this year," David Rose, a teacher at Roberto Clemente Community Academy told NBCChicago.com. "The posturing of the board of education has created such misery and suffering and discontent that we needed to send a message."
Financial reports show the school system has a $700 million budget shortfall.
The Associated Press contributed to this report.
More content from msnbc.com and NBC News:
- US Commerce secretary in car crashes suffered a seizure
- Chicago's bloody weekend: 8 dead, 40-plus wounded
- Sandusky child sex-abuse trial under way
- 3 killed, 3 wounded in shooting near Auburn University
- Report: NYPD fires Orthodox Jew recruit for refusing to trim beard
- Video: Stepfather in hot water for child beating