CHICAGO (CBS) — Mayoral hopeful Jesus “Chuy” Garcia has scoffed at accusations he will be beholden to public employee unions that have backed him in his bid to unseat Mayor Rahm Emanuel, because of the substantial cash they’ve given Garcia’s campaign.

Garcia acknowledged the Service Employees International Union and Chicago Teachers Union have had an acrimonious relationship with Emanuel, and that’s one reason they’re supporting him. But he said the city’s plunging bond ratings and tight budget mean he can’t give the unions everything they want in any contract negotiations if he’s elected mayor.

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“As we move forward, we’re going to have to have some very tough conversations. Am I prepared to do that? Yes. Except that my approach will be collaborative. Probably no one will be happy as we move forward for the first few years, but we’re going to do things with transparency, with ethics,” he said.

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Garcia said the city is in a financial freefall, thanks to Emanuel, and that means unions will have to give up concessions at the bargaining table.

“That will require for there to be some very tough conversations for some tough medicine to be swallowed by all of the partners. So there’s no gravy to go around. It’s going to be difficult moving forward,” he said.

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The mayoral challenger will be one of the guests on a pre-election edition of “At Issue,” airing Sunday at 9:30 a.m. and 9:30 p.m. on WBBM Newsradio 780 & 105.9FM.