Obamacare took a big step forward on Tuesday night, when the Michigan Senate approved an expansion of the state’s Medicaid program. The state House is likely to back the same measure, as early as next week. And while the program requires a special federal waiver, the Obama Administration is likely to grant it. Assuming all of that happens, Michigan will become the twenty-fifth state to expand Medicaid as part of the Affordable Care Act. As a result, a few hundred thousand residents are likely to get insurance—and the state will get a much-appreciated infusion of federal funds, while putting up a much smaller share of state money.

For the advocates of making health insurance available to all Americans, it’s a huge victory. But the victory did not come easy—or without some last-minute drama.

Tuesday’s vote was the product of a long, sustained campaign by Democrats, moderate Republicans, progressive organizers and business leaders. For months, they have made the case for expansion—citing the likely financial and health benefits for Michigan’s uninsured citizens, and the expected boost to Michigan’s economy. The federal government is picking up most of the expansion’s costs, they have argued, and hospitals need the revenue to make up for money they lost on charity care and declining reimbursement from other sources.

Among those assessing the statistical impact were Marianne Udow-Phillips, director at the Center for Healthcare Research and Transformation and a lecturer at the University of Michigan School of Public Health. As she told me on Wednesday,

if you look at all the facts—the fact that the majority of physicians in the state are ready to serve this population; the positive impact on the state budget, on the state's economy at large, on hospitals, on businesses, on all those who are currently insured (by reducing cost shifting) - not to mention the half a million people who will directly benefit by getting health insurance coverage in a program that has the highest satisfaction of any insurance coverage type in the state – you have to draw the conclusion that the Medicaid expansion is the right thing to do for the state.

Governor Rick Snyder and the state Chamber of Commerce have been among the strongest proponents of expansion. The state's health care industry, naturally, has lobbied furiously. But Tea Party Republicans and their allies have been dead set againt it, arguing that Medicaid is a wasteful, expensive program that subsidizes the indolent—and that the size of the federal subsidies masked the true impact on the state, which would actually be negative.