She’d written the same post two years earlier and hadn’t gotten a single reply. But 2016 was different: People everywhere were newly engaged in politics, debating one another and demanding fundamental changes in their government. Voters in Michigan’s primaries that year had chosen the anti-establishment candidates, Donald Trump and Bernie Sanders. “These two candidates are talking about taking down the system, this extreme overhaul,” Ms. Fahey said. “It seems like people are really hungry for that.”

Her Facebook post went viral. A nonprofit group, Voters Not Politicians, was born. Its goal: getting a constitutional amendment on the 2018 ballot that would take map-drawing power from lawmakers — who would never relinquish it themselves — and give it to a commission made up of regular citizens who would consult with data analysts and present their progress in regular public hearings. Independent redistricting commissions, which are already functioning in California, Arizona, and four other states, can go a long way toward reducing the influence of partisan politics in mapmaking.

The Michigan proposal would establish a 13-member commission made up of four Republican voters, four Democratic voters and five independents.

The group initially scheduled eight town halls to make its case to the public. They ended up holding 33 in 33 days. “A bunch of us with day jobs, speeding to northern Michigan after work, trying to find a public library to host the town hall in, because we don’t have any money,” Ms. Fahey said, recalling the hectic early days of the movement. “We basically crowdsourced the campaign. Because I’m a millennial, I figured this is how things work.”

She was right. Less than two years after her Facebook post, Ms. Fahey leads a volunteer army of 10, 000 Michiganders representing every county in the state. Five thousand of the volunteers work daily, knocking on doors, educating voters and gaining support for the initiative. Michigan requires citizen ballot measures to get 315,000 signatures; in December, Ms. Fahey’s group submitted more than 425,000. In June, the state approved the measure and added it to the ballot.

Even Ms. Fahey’s family is on board. Her mother, who had no idea what redistricting was, personally gathered 700 signatures. So far, the group has raised about $1.25 million, far less than most citizen-led initiatives, and yet it has 14 times more individual donors than any other Michigan initiative this year .

The initiative looks like a prime example of regular citizens rising up and making their voices heard when lawmakers are ignoring them. But the tight web of money and politics that has entrenched Michigan Republicans in power isn’t tearing easily. The state Republican Party and its top politicians, including Bill Schuette, the attorney general now running for governor, are working hard to have the initiative struck from the November ballot. They’ve taken their fight to the Michigan Supreme Court, which heard oral arguments last week . The court is expected to rule by the end of July.