The confrontation between striking teachers and Chicago Mayor Rahm Emanuel moved to court on Monday where lawyers for the mayor sought to stop the walkout in President Barack Obama's home city just weeks before the November 6 election.

Lawyers for Chicago Public Schools filed a complaint in circuit court against the Chicago Teachers Union seeking a preliminary injunction "to end the strike immediately" citing two reasons: danger to "public health and safety" of the students and alleged violation of Illinois state law that prohibits strikes except for wages and benefits.

"State law expressly prohibits the CTU from striking over non-economic issues, such as layoff and recall policies, teacher evaluations, class sizes and the length of the school day and year. The CTU's repeated statements and recent advertising campaign have made clear that these are exactly the subjects over which the CTU is striking," the school district said in a statement.

It was not clear when the court would schedule a hearing on the complaint, but lawyers expected one later on Monday.

The dispute between Emanuel, a former top White House aide to Obama, and organized labor had been close to resolution on Sunday when top union leaders recommended to a meeting of union activists that the 5-day strike be suspended.

But a majority of the 800 or so union delegates, wary of promises made by Emanuel and Chicago Public Schools, ignored the leadership and extended the strike until at least Tuesday.

The famously short-tempered Emanuel immediately issued a statement saying he would go to court to try to have the strike declared illegal.

"We are done negotiating," Chicago Board of Education president David Vitale said on Monday.

UNCHARTED TERRITORY

Emanuel's move took the dispute into unchartered territory as no injunction request has been filed in an Illinois education labor dispute since 1984, when the state gave Chicago teachers the right to strike. It also deepens the rift between the Democratic mayor, a top fund raiser for Obama's campaign, and a labor group that generally backs Democratic candidates.

Some 29,000 public school teachers and support staff have been on strike since September 10 over Emanuel's demand for sweeping education reforms.

Strikes in the United States usually are over wages and benefits but Emanuel is offering an average pay rise of more than 17 percent over four years, which the union accepts.

The surprise developments on Sunday raised questions about how parents of the 350,000 of children out of school would react and how union members would respond to Emanuel's legal move.

"I do think going into the second week there is concern about the children being out of school longer and losing the good will of the public," said DePaul University professor Andrea Kayne Kaufman. "Like everyone else, I was disappointed that there wasn't a ratification."

Opinion polls last week showed Chicago voters supporting the union, but that could change as the strike drags on.

Willie Nawls, who has four children in Chicago public schools, said he has been fortunate because his two oldest children in high school could take care of the younger two.

"I'm very upset," he said of the strike. "I'll be patient with the union and see what they try to work out."

The mayor's negotiators and the union had worked out a compromise agreement on Friday that they hoped would end the strike. As part of the deal, Emanuel backed off some of his demands on teacher evaluations, agreeing to phase in the use of student testing to review teachers and dropping his insistence on pay based on merit.

The showdown has highlighted a national debate over how to improve failing inner city schools. Like Chicago, many major city school districts are losing students to the suburbs and have a high percentage of children from low-income households.

Emanuel, backed by a coalition of financiers and philanthropists, believes that the best way to improve the schools is to set higher standards for teachers and to close low-performing schools and replace the staff.

The union wants cities to invest in traditional neighborhood schools and teacher training rather than closing them down. The children live in poor and crime-ridden neighborhoods and need more support to succeed, the union says.

Chicago teachers mistrust Emanuel and the school district because scores of schools have been closed in recent years. They fear Emanuel will close up to 20 percent of Chicago schools once the strike ends, which would lead to mass layoffs of unionized teachers.

They accuse Emanuel of trying to "privatize" public education by allowing outside groups to run some "charter" or "contract" schools outside the union but financed with public funds.

The dispute has become personal, with union leader Karen Lewis calling Emanuel a "bully" and a "liar." Lewis has said Emanuel does not show the union proper respect and his policies will have disastrous effects in poor communities.

Racial tension has been a backdrop to the disagreement, with the union saying a disproportionate number of African-American teachers have been laid off as schools are closed.