Michigan AFSCME Council 25 says it will challenge the state's new prison food contract with Trinity Services Group.
The state announced the deal with the private Florida-based company Monday after ending ties with Aramark over months of complaints.
Nick Ciaramitaro, legislative director for AFSCME Council 25, said handing the contract over without first opening it up to other bidders is unlawful.
"We're simply exchanging one private vendor for another with no evidence that things are going to improve," Ciaramitaro said.
Trinity Services Group bid on Michigan's prison food contract in 2013, before it went to Aramark for $145 million.
Ciaramitaro said the state's new three-year $158 million deal with Trinity is "penny wise, pound foolish."
"It took all of a half an hour and a Google search to find that Trinity was facing the same sort of charges in jails in other states that had created such a fear over Aramark," he said.
Trinity is set to take over for Aramark in September.