(CBS) – Second Ward Ald. Bob Fioretti made it official Saturday, announcing he will run for mayor and challenge incumbent Rahm Emanuel in 2015.

As supporters gathered in a South Loop gym on Wabash Street, chanting “Bob!”, Fioretti said the story of Chicago under Emanuel has been a tale of two cities.

There are haves and have-nots, he said, and the have-nots have been ignored by the mayor.  “He looks out for some of us,” Fioretti said, “and lets us all down.”

Emanuel has failed Chicagoans on crime, Fioretti said, and schools, jobs and mental health.

Fioretti has suggested doing away with the hated red-light cameras installed across the city, but he didn’t mention them during his campaign announcement.

He did say that the 600,000 commuters who come to the city to work each day should pay a 1 percent commuter tax, to help cover the costs of making the city livable.

Fioretti’s campaign website signaled his announcement overnight.

“Four years ago, a new mayor came in and asked for our vote. He promised us safer streets, stronger schools and a more stable economy. Sadly, he has failed us by every measure. Chicago needs a change for the better,” Fioretti says in a video posted on the site.

Fioretti, a civil-rights attorney, was first elected in 2007 and is a cancer survivor. He represents a diverse ward that surrounds the downtown.

“This is a great day for Chicago. It’s a great day to see people stepping up, providing leadership in a city that so desperately needs it,” fellow Emanuel critic, 32nd Ward Ald. Scott Waguespack, told the crowd of Fioretti supporters.

Emanuel’s campaign issued a critical response to Fioretti’s announcement.

“Time and again, Alderman Fioretti has shown no backbone for making tough choices and little respect for Chicago taxpayers’ pocketbooks. Chicago can’t tax itself out of its problems. Chicago needs, and has, a strong leader who has shown that he is willing to make tough decisions,” Emanuel campaign spokesman Steve Mayberry said.

Emanuel faces low poll numbers and controversy on multiple fronts as he prepares a run for re-election. But he reportedly has more than $7 million in his campaign coffers, compared to Fioretti’s $300,000.

Another potential challenger is Chicago Teachers Union president Karen Lewis, who is critical of Emanuel for closing several public schools under a consolidation plan.