CHICAGO (CBS) — As a fourth school in Chicago voted to accept a longer school day, the City Council gave its unanimous support to the push to add at least 90 minutes to the school day at Chicago Public Schools.

WBBM Newsradio Political Editor Craig Dellimore reports that aldermen voted unanimously Thursday in favor of a resolution supporting the longer school day for public school children.

“This is a defining moment in our history, ladies and gentlemen,” Ald. Willie Cochran (20th) said.

LISTEN: WBBM Newsradio Political Editor Craig Dellimore reports

The nonbinding resolution carries no legal weight, but does urge the Board of Education to lengthen the school day “as soon as possible.”

But a few aldermen seemed ill at ease with Emanuel offering incentives for teachers and staff at individual schools that vote to adopt the longer school day.

“This should not be done one school at a time, this should not be done one community at a time, it should be done as one city,” said Ald. Harry Osterman (48th)

Earlier in the day, teachers at Benjamin E. Mays Elementary Academy in Englewood voted to adopt a longer school day there, becoming the fourth school to do so.

Mayor Rahm Emanuel and CPS Chief Executive Officer Jean-Claude Brizard have been offering incentives to all schools that opt for a longer school day this year – including $150,000 for each school and a bonus of $1,250 to the teachers. Schools making the switch would get $75,000 and their teachers would get an $800 bonus.

At Thursday’s City Council meeting, Ald. Edward Burke (14th), a big union backer, said he was starting to be embarrassed by some union leaders who seemed to be trying to obstruct a longer day – a clear jab at the leadership of the Chicago Teachers Union.

But the union said the council’s vote was nothing more than an “empty political gesture.”

“It is unfortunate the City Council bowed to the pressure of a well-orchestrated propaganda campaign that has no scientific evidence to show that this will do anything to improve the quality of education in our neighborhood schools,” union officials said in a prepared statement. “It is shameful that not one politician stood up for our students and teachers who deserve better. A longer school day is inevitable but how will it be funded and how will it be planned?”

The union said it supports a longer school day, but wants to ensure it comes with the proper curriculum and that teachers are paid appropriately for the extra work. The union has been pushing to spend the extra time on subjects like art, music, world languages, civics and science.

“The longer school day campaign is nothing more than a political gimmick based on lies, misinformation and half-truths. And a gimmick, even if CPS calls it ‘education reform,’ harms the children of Chicago,” the union said. “They need rich, thoughtful learning, not empty political gestures.”

The union has rejected an offer from Emanuel to give elementary school teachers a 2 percent raise in exchange for a longer school day this year. The offer came weeks after Emanuel and Brizard cancelled negotiated 4 percent raises for all teachers, citing the district’s $700 million budget shortfall.