GROSSE POINTE PARK, Mich. -

A marijuana decriminalization measure isn't expected to be on the November ballot in Grosse Pointe Park following a mistake by organizers of the effort.

Safer Michigan Coalition, a Detroit-based nonprofit coordinating petition drives around Michigan, collected hundreds of signatures.

However, Grosse Pointe Park officials found an incorrect date on one set of signatures that invalided the petition drive. Coalition co-founder Tim Beck says he mistakenly put the incorrect date on the form.

City officials say the date invalidated 106 of 596 signatures, making the total 490 -- fewer than the 495 needed to get on the ballot.

Supporters of marijuana decriminalization previously said the vote would mark a possible tipping point in the debate over the drug in Michigan.