Lansing — Organizers seeking to put a $12 minimum wage question on the November ballot will sue Michigan’s Republican-led Legislature if lawmakers adopt the proposal only to later undermine it, the group’s attorney said Tuesday.

Mark Brewer, legal counsel for the One Fair Wage committee, threatened legal action Tuesday outside the Michigan Capitol as lawmakers prepare to return for session days Wednesday and Thursday — their last meetings before the state election officials finalize the fall ballot.

As The Detroit News reported last week, Republicans are considering whether to approve the minimum wage proposal and a separate paid sick leave initiative, both of which are the on the tentative state House agenda for Wednesday.

Adopting the measures would keep them off the ballot and make them easier to amend in the future. But doing so in the same two-year legislative session would be unprecedented and unconstitutional, argued Brewer, former chairman of the Michigan Democratic Party.

“We want to send a very loud and clear message this morning that if the Legislature adopts this proposal and in any way weakens it during lame duck, we will sue,” he said. “And we believe we will successfully defend the people’s right of initiative in this state and prevent the Legislature from undermining the initiative process.”

The Michigan Constitution of 1963 gives lawmakers 40 days to adopt legislation initiated by citizen petition drive, do nothing and let it go to the ballot or propose an alternative and send both to the ballot.

Brewer and other opponents of the adopt-and-amend strategy — which Republicans also considered earlier this year for a marijuana legalization initiative that is now Proposal 1 — point to a 1964 legal opinion from Democratic then-Attorney General Frank Kelley.

It is “clear that the Legislature enacting an initiative proposal cannot amend the law so enacted at the same legislative session without violation of the spirit and letter of Article II, Sec. 9 of the Michigan Constitution,” Kelley wrote.

But attorneys for Michigan Opportunity, an opposition campaign fighting the proposal and its elimination of a lower tipped wage for restaurant servers, argue “the gratuitous statement set forth in the 1964 AG opinion is clearly incorrect,” contradicting both “the letter and spirit” of the state Constitution.

“Legislatively adopted initiatives are to be treated exactly the same as laws enacted by the Legislature in the normal courts,” according to a memo from the Honigman law firm. “Such laws may be amended by a majority vote at any time.”

By contrast, any law directly approved by voters at the ballot box can only be amended by a three-fourths majority in both chambers.

Kelley's 1964 legal opinion has never been tested “because the Legislature has never been arrogant enough to try this,” Brewer said. The current two-year session ends at the end of the year, and November elections could reshape the power structure in Lansing.

Senate Majority Leader Arlan Meekhof, a West Olive Republican who led a failed effort to adopt and amend the marijuana proposal in June, “is aware of the opposition to the adoption of the initiative and the legal assumptions made by the minimum wage group,” said spokeswoman Amber McCann.

Senate attorneys have reviewed the legal questions and Republicans are confident they have the authority to act, she said.

House Republicans are expected to meet outside the Capitol on Tuesday to discuss potential action on the minimum wage and paid sick leave proposals.

House GOP legal counsel is “looking into” the constitutional questions, “but the first priority is to determine whether or not the bills need work from their current form,” said spokesman Gideon D’Assandro. “That is the first issue that will be determined.”

Sen. Mike Shirkey, R-Clarklake, said Tuesday he was “hearing lots of opinions” about the adopt-and-amend strategy. He personally supports the effort, particularly on the paid sick leave proposal, which he said last week would send a “very negative sign to businesses considering investing capital in Michigan.”

The Secretary of State’s Office plans to put both measures on the ballot if lawmakers do not act on them this week. The Legislature technically has until early October to consider the minimum wage proposal, and it’s not clear what would happen if lawmakers adopted it after it was already placed on the ballot.

“That’s a good question for constitutional scholars,” said Secretary of State spokesman Fred Woodhams. “I don’t know.”

The minimum wage proposal is also facing a legal challenge that could still keep it off the ballot. An opposition group had asked the Michigan Supreme Court to weigh in on its appeal by the end of last week, but justices have not yet responded.

The One Fair Wage proposal would raise Michigan’s $9.25-an-hour minimum wage to $10 in 2019, $10.65 in 2020, $11.35 in 2021 and $12 in 2022. Any future increases after 2022 would be tied to inflation.

The proposal would also phase out the lower $3.52 minimum wage for restaurant servers and other tipped employees, bringing it up to $12 by 2024.That provision has sparked aggressive opposition from the restaurant lobby and some restaurant workers who fear it may discourage tipping in the future.

The MI Time to Care proposal would require Michigan businesses to provide workers with paid sick leave they could use in case of physical or mental illness, injury or health conditions affecting themselves or a family member. Time off also could be used by victims of domestic violence and parents attending school meetings.

The Michigan Chamber of Commerce, which opposes both proposals, “is certainly open” to lawmakers adopting the measures in order to clean up definitions and improve them, said President and CEO Rich Studley.

“I don’t think it’s in anybody’s interest to have unworkable, impractical legislation that fails to meet its promises with employees and then saddles employers with administrative nightmares and legal burdens,” Studley said.

The minimum wage ballot committee, backed by the national Restaurant Opportunity Center and United Auto Workers union, collected an estimated 283,544 valid signatures to place the measure on the ballot.

The Board of State Canvassers is set to meet again on Thursday and Friday — the deadline — to consider outstanding ballot issues.

Lawmakers “know that working people, people of color, young people and women are going to go to the polls in November if they know they can vote themselves a raise,” said minimum wage campaign director Pete Vargas. “Anything less than that from our legislators is a clear suppression of our vote and a clear disenfranchisement of voters.”

joosting@detroitnews.com