Fioretti first talked about his possible candidacy for mayor on ABC7 last year. Monday he got some encouragement from a powerful union leader to challenge Emanuel.
"I will make the announcement at the appropriate time," Fioretti said.
Fioretti said he's still considering a run for mayor in 2015. To an audience of civic, business and political leaders, the Second Ward alderman questioned Emanuel's competence for closing half the city's mental health treatment centers and dozens of public schools.
"If you close schools in communities and 20,000 people come out, you shouldn't be mayor," Fioretti said.
"He hit all the right notes and I hope he decides to run," said Karen Lewis, leader of the Chicago Teachers Union (CTU).
Lewis and the CTU will consider several candidates they would support against Emanuel next February.
Fioretti's second ward – which used to be on the Near South and West sides – was re-mapped to the North Side by the Emanuel-controlled Chicago City Council.
Political science Professor Paul Green said in any event, Fioretti must restart with voters.
"He's got to make a decision - run again in a new ward like the second or go for mayor," Green, a professor at Roosevelt University, said.
Cook County Board President Toni Preckwinkle, who's running for re-election this year, has not ruled out a run for mayor.
"We have a continuing dialogue," Fioretti said about Preckwinkle. "We see each other often. We sit down and talk about where we're going and what her aims are."
Fioretti would not answer when asked directly if he and Preckwinkle had discussed whether one or the other would challenge Emanuel in 2015. One poll reported last month suggested that Preckwinkle is leading Emanuel in a one-on-one race.