While public employee unions and municipal organizations split over House Speaker Andy Dillon’s proposed plan to combine all state employees under a single health insurance plan, a new study has concluded that the plan would not save the state money and would in fact cost hundreds of millions of dollars in the first year alone. The Detroit Free Press reports:

An analysis by Public Policy Associates concludes that Dillon’s plan would save money largely by reducing benefits for an estimated 500,000 public workers, or require them to pay more for health insurance than they do now.

Dillon has claimed his plan would save the state, schools and local governments a combined $1 billion a year by creating a massive insurance pool of some 500,000 public employees.

“We find the savings … are largely illusory, especially those related to administrative efficiencies and economies of scale,” wrote Doug Drake, researcher for the study.

The study says Dillon’s plan would cost taxpayers $500 million to launch, and up to $370 million a year to administer.

Dillon’s plan has been wildly unpopular with traditional Democratic constituencies like unions. That proposal, along with Dillon’s ill-fated agreement with Senate Majority Leader Mike Bishop to attempt to balance the budget solely with cuts to key state programs, has Dillon’s stock within his own party at an all-time low.