Traditionally, state attorneys general speak out only on matters of direct concern to their offices — enforcing the laws, protecting citizens’ rights under the law, and determining whether a particular bill or proposal would violate the federal or state constitution.

So it was startling last week when Michigan Attorney General Bill Schuette denounced a May 5 ballot proposal that would raise the state’s sales tax from 6 to 7 percent, primarily to pay to repair crumbling roads. “I understand that Michigan’s roads need to be rebuilt,” he said, but asserted that Proposal 1 “has a lot of potholes and pitfalls.” He offered no hint of what he would do instead to fix the state’s roads, and how to pay for that.

By implication, Mr. Schuette, a Republican, seemed to attack Rick Snyder, the state’s Republican governor, who supports the ballot plan. Frank Kelley, who was Michigan’s attorney general for a record 37 years, said he was astonished by Mr. Schuette’s actions. He added that he never spoke out against any policy of any governor of either party, unless he had to.

Mr. Schuette appears to be courting Michigan Tea Party voters for their support if he runs for governor, as expected, in 2018. Last year, on another hot-button issue, he was so zealous in fighting against legalizing same-sex marriage and adoption that some of his “expert” witnesses were not allowed to testify in federal court because a judge ruled them unqualified.

It’s not clear whether this is good politics — that’s debatable — but it is wrong-headed and divisive. Mr. Schuette should concentrate on being a full-time attorney general. Michigan doesn’t seem to have run out of crime.

First Published March 10, 2015, 4:00 a.m.