GRAND RAPIDS, Mich. – Attorney General Bill Schuette and three law enforcement officers are urging parents to vote against Proposal 2 in a new ad, saying the union-backed measure will make school less safe.

But a state parents group is siding with unions and Democrats backing the proposal, saying the ad campaign by opponents relies on “offensive” scare tactics.

Proposal 2, also called Protect Our Jobs and Protecting Working Families, is intended to enshrine collective bargaining in the state constitution.

Schuette said the proposal will have a “devastating effect” on 170 state laws, including “many that keep Michigan kids safe at school like laws establishing minimum safety training standards for bus drivers and empowering school districts to immediately remove teachers from the classroom who have been caught under the influence or selling drugs at school,” according to a release from Citizens Protecting Michigan’s Constitution.

The group is a coalition of business, school and community organizations.

"It is our job to protect Michiganders but Proposal 2 would tie our hands," Ionia County Sheriff Dwain Dennis said in a release. "Take it from me—Proposal 2 is dangerous."

The ad includes Schuette, Dennis, Livingston County Undersheriff Mike Murphy and Oakland County Deputy Terry Fortuna.

RELATED: Michigan Decides 2012: Proposal 2 would put collective bargaining in Constitution; does it belong there?

Proposal 2 backers picked up the support of the Michigan Parent Teacher Association. President Shaton Berry denounced the opposition as "corporate special interests" trying to "silence the voices of working families" and "corporate bosses hide behind shadowy front groups."

“The scare tactics Proposal 2’s opponents are using on Michigan’s voters are frankly, offensive,” Berry said in a release.

“The idea that Proposal 2 would make it harder to remove felons or sex offenders from our classrooms is a complete lie and the Michigan Court of Appeals agrees that Proposal 2 does not impact school safety. No teacher, school board member or superintendent wants to protect felons or sexual predators, nor would they ever attempt to do so at the bargaining table.”

Michigan PTA President-elect Teresa Marhofer said collective bargaining gives families a “voice to negotiate for fair wages, benefits and working conditions that are good for us all. It gives firefighters and police officers a voice to negotiate for life-saving equipment and protects nurses who speak up about a patient’s care.”

“Our communities lose when we remove the voice of teachers and other respected public servants like firefighters, police, and nurses, who bargain for working conditions that keep children and families safe,” said Michigan PTA President Elect Teresa Marhofer.

Collective bargaining gives Michigan’s working families a voice to negotiate for fair wages, benefits and working conditions that are good for us all. It gives firefighters and police officers a voice to negotiate for life-saving equipment and protects nurses who speak up about a patient’s care.

The group also has announced support from Wayne County Sheriff Benny Napoleon, Macomb County Prosecutor Eric Smith and former Gov. Jennifer Granholm.

Email Dave Murray at dmurray@mlive.com and follow him on Twitter @ReporterDMurray or on Facebook.