Several unions and the heads of the Fraternal Order of Police and Firefighters union are upset about the ad, which is running on TV. It suggests city workers could use "a different mindset."
The ad began airing last Friday as city workers struggled to clear side streets and alleyways blocked by the third worst snowfall in Chicago history. In the commercial, Emanuel suggests Chicago's public employees think differently about their taxpayer-supported jobs.
"I want that mindset to be different," Emanuel said in the ad.
"Somehow Chicago employees have become the demons in this election," Jim Sweeney, Operating Engineers Union, said.
Several union leaders who announced their support Monday for Chicago mayoral hopeful Gery Chico were outraged by the Emanuel ad.
"Our members are gonna be informed now where Rahm Emanuel stands on issues that are important to us," Sweeney said.
"Let me set something straight right now. Rahm Emanuel is sticking it to the working class of this city," Gery Chico, mayoral candidate, said.
Emanuel -- who has been endorsed by the teamsters and several trade unions -- explained what he as mayor would demand as a "mindset" for public employees.
"The people that worked all the way down the line will all adopt a mindset of public service and that the taxpayers are the ultimate bosses," said Emanuel.
One day after Emanuel's campaign began running the ad, a city worker shoveling snow died of a heart attack. The fraternal order of police issued a statement noting that eight public safety workers have died in the line of duty in the past year and the firefighters union president said his members need no change in their "mindset."
"I don't think anyone can ever question our resolve and our dedication to the citizens of the city," said Tom Ryan, IAF Local NO. 2.
Also on Monday, Emanuel was endorsed by Illinois Secretary of State Jesse White. It was the former congressman's first endorsement by an African-American elected official.
"Yes, you're absolutely correct. I happen to be the only one. And I'm proud to do it, sir. I make no apologies for my commitment to this gentleman," White said.