"We made a serious offer," Emanuel said.
"This is what I call a win-win for the city of Chicago," he said, speaking at an annual breakfast for interfaith leaders at U.S. Cellular Field.
Emanuel asked ministers to talk in their Sunday sermons about school starting Sept. 6 and about the need for a longer school day. The mayor campaigned on a promise to support an extra 90 minutes to the school day and two weeks to the school year.
Schools Chief Jean-Claude Brizard also attended the event, which brought out 250 pastors from groups like Partners United for Change and Hispanic Leaders for Change. He said he has not heard a formal union response to his offer to give elementary teachers the raises if they agreed to start the longer school day in January.
"We want to make this happen next year," Brizard said. "We'd love to make this happen this year."
Should any agreement be reached with the union, officials will need to make $15 million in cuts to pay for the additional time in the classroom, CPS officials said.
The faith leaders have also collected more than 200 signatures on petitions in support of the longer day.