A potential ballot proposal to change Michigan’s campaign finance law could upend political giving and advertising in the state, hamstringing prolific political donors and revealing major sources of “dark money” spending.

A coalition of interest groups has formed Michiganders for Money Out of Politics, a committee seeking to put a proposal on the 2026 ballot that would ban regulated utilities and state government contractors — along with their senior employees — from making contributions to state candidatesand a broad array of other political spending.

But the proposal would also go further, requiring any outside spending group making even tangential reference to a candidate or ballot issue to report their spending totals and donors to the state in the months leading up to an election.

At least 11 other states require donor transparency for so-called issue advertisements that have evaded disclosure rules in other parts of the country, but Michigan would be the first political battleground to do so.

“We’re doing everything we can to close those loopholes,” Sean McBrearty, the Michigan state director of Clean Water Action, said in an interview. “I think that this will be a major step towards building a better and more transparent government in Michigan.”