The City Council on Tuesday approved a resolution opposing a bill by state Senator Brian Kelsey that would bar governments from working with unions.
City Councilman Chris Anderson earlier held a press conference to call the bill "a power grab by politicians."
He said he and others were urging legislators not to go along with the bill that is expected to be aired in a Senate committee soon.
Councilman Anderson said the city and its government have "flourished" under a system in which unions "are at the table."
He said if the bill passes that the local firefighters would no longer be able to hold a Christmas fundraiser to benefit children.
Councilman Anderson said Senate Bill 123 "substitutes Nashville politicians' values in place of our Chattanooga values and would have blocked some of our most important achievements in city government.
"It needlessly encourages litigation and ignores our city charter.
"It authorizes officials from the county and state governments to sue the city."