In some ways, said Tom Buchmueller, a health economist at the University of Michigan Ross School of Business, those proposals could have even more immediate impact than the public option by strengthening a system that already covers nearly 275,000 Michiganders – with another 674,000 state residents on Healthy Michigan, the Medicaid expansion plan created under the ACA as well. ¶¶”As a practical matter, it would be much easier to tweak the parameters of the Obamacare system to expand coverage. There are real advantages to building on that system,” he said.