In the spring of this year, Julie Falbaum’s 20-year-old son walked into a frat party filled with about 50 of his peers, holding a stack of petitions. They were for a campaign to protect abortion.

“Who wants to be a dad?” he yelled. Like a park-goer throwing bread to pigeons, he chucked the forms around the room and watched as dozens of young men swarmed to sign them.

The campaign to enshrine abortion rights in the state constitution was already under way here even before Roe fell, and it has become an embittered battle in Michigan – to keep a 90-year-old abortion ban off the books. Campaigners fear that ban would criminalise doctors and pregnant people and deny essential medical care, such as miscarriage medication, now that the constitutional right to abortion no longer exists in the US.

The battle in Michigan has seen death threats and vandalism from pro-choice militants. On the anti-choice side, it has involved dirty tactics from the Republican party, who tried to block a petition brought by nearly 800,000 Michiganders over formatting errors, and who have peddled a wide campaign of misinformation.

Julie Falbaum, a campaigner for the yes campaign on Proposal 3, which would enshrine reproductive rights, believes her son’s story – that he managed to collect so many signatures at a frat party without a campaign plan – is reflective of a broad coalition of support for “Prop 3”, which is supported by men and women, young people and older people, Republicans and Democrats.

“I see Michigan as pivotal to the future of democracy in the United States,” says Deirdre Roney, 60, who travelled from Los Angeles to campaign for the ballot in Detroit, where she grew up. Explaining that Detroit is the biggest voting bloc in Michigan, and that Michigan is one of the swingiest states in the country, she adds: “This is a blueprint. If this passes in Michigan, other states can use it.”

Indeed, Michigan’s elections are at the center of a national abortion debate that has spiraled to extremes. Since the constitutional right to abortion fell on 24 June, almost half of US states have banned it, or tried to.

“I wouldn’t be surprised if there are more votes for [Proposal] 3 than for the governor’s race,” says Jeff Timmer, a senior adviser for the Lincoln Project, a coalition of Republicans and former Republicans who campaign to keep Trump out of office.

Timmer, who was a Republican party strategist for more than 30 years, says statewide abortion bans are turning people off the party.

“The Republicans have used abortion for decades as a means to motivate their pro-life religious base. And for most everybody who was engaged in that rhetoric, it was always theoretical. They never really had to worry about real-life consequences – and now they do,” says Timmer.

“It’s a simple question of: how long should my daughter, my sister, my wife, my granddaughter go to prison? Should my doctor go to prison? Quite honestly, that’s crazy. Most rational people would say no to that.”

Alisha Mcneeli, 44, a lifelong Republican who lives in Grand Rapids, Michigan, will be voting for the proposal, which also enshrines contraception rights and IVF.

“I have always been a pro-choice Republican,” says Mcneeli, 44, a community outreach director for the Michigan child protection registry.

“Since I’ve become a mother, I’m more pro-choice than ever. Being a parent is the hardest thing – physically, emotionally and financially – that I’ve ever done in my life. I wholeheartedly believe that if a woman is not ready, she should not be forced to.”

A 2016 Trump voter, Mcneeli will also vote Democratic for her national representatives in the midterms. She says Lindsey Graham touting a national 15-week ban on abortion – a proposal that didn’t pass in the Senate – could be enough to turn her away from the party for ever.

“I feel like I’m slowly already doing that. He promised this was not going to even be talked about at the federal level. He completely lied. That makes me sick, I’m so angry about it,” she said.

Falbaum says the biggest change in attitude she has seen since she started working on the petition earlier this year is the gender split.

“In the past, it was a woman’s issue. It was: ‘Talk to my wife, my girlfriend, I don’t know about those things.’ And now I hear men not only understanding that it’s not a woman’s issue, but actively supporting it,” explains Falbaum.

Jeff Bolanger, 69, is one of them. He lives in downtown Ann Arbor, a small and relatively liberal city near Detroit that is home to the University of Michigan. “I don’t really think it’s appropriate to control people’s choices about that,” Bolanger said.

Joaquin Gabaldon, 30, also says he’s voting yes when Falbaum and Roney knock his door.

“I mean it’s healthcare, it’s rather straightforward,” he said.

In Wayne county’s Grosse Point, a wealthy, mostly white, mostly Democratic area that has recently seen more election deniers and Trump supporters, several people on the doorstep said they hadn’t heard of Proposal 3, but would support it in theory. In suburban Sterling Heights, in the divided Macomb county, Ed Bristow, 60, who works in human resources, opposes Proposal 3: “It just cuts into the sovereignty of the family unit.”

Democrats in Michigan joke that the signage of the no campaign – “Vote no. Too confusing. Too extreme” – makes them look silly: absent a real critique of the ballot initiative, instead they focus on making voters feel they can’t understand for themselves. But a lot of emotive misinformation is circulating, including materials from the Catholic church that suggest a number of policies could arise from voting yes including child sterilisation and abortion without parental consent – none of which has been proposed.

Darci McConnell, the communications director for the yes campaign, cites recent polling showing 64% of Michiganders support Proposal 3. “They’re very invested in misinformation, because they know people don’t want to ban abortion – that a 1931 law has no support,” she says of the no campaign.

“There’s been a lot of misinformation,” says Pastor John Duckworth of Wayne county. “People have been saying you don’t have to be a doctor to perform an abortion [under Proposal] 3. They’re talking about gender reassignment surgery. None of that is true.”

Referring to African Americans, he said: “There weren’t many laws from 1931 that benefited my community.

“Now of course, [black voters] are not a monolith,” he added. “But alongside Roe came protections for gay marriage, for interracial marriage, for contraception … This is about civil rights. For people who have had their bodies controlled for hundreds of years, this is very scary.”

Falbaum described a middle-aged man she saw on the day the supreme court decision leaked. She went out to set up her petition stand to get abortion on the ballot at a farmer’s market in downtown Ann Arbor – only someone had gotten there before her.

“I said, ‘You’re first in line for the concert tickets!’” jokes Falbaum. “And he tells me his mom died in a back alley abortion, protecting him and his siblings before Roe was passed – because she knew she could not support another child. To honour her memory, he wanted to be first to sign the petition.”

How will she feel if Michigan votes yes on 8 November, as the polls suggest?

“It feels like a culmination of my life’s work,” says Falbaum, tearing up. “It just makes me feel safe.”