DTE Energy and Consumers Energy are among the nation’s largest utility companies, and are unpopular in Michigan because, federal data shows, the state over the last decade has had among the nation’s highest rates and worst-in-the-nation reliability. The utilities are prolific campaign donors, and their contributions are thought to be the reason why reform legislation has always failed.

The revelations also come as a first-in-the-nation citizen’s ballot initiative to ban political donations by utilities picks up steam, and advocates say the investigation underscores the need for the legislation.

The “lack of transparency” is especially a problem because the utilities operate as a regulated monopoly, so political oversight is critical, said Nick Dodge, spokesperson for the Michigan League of Conservation Voters, which is on the steering committee for the ballot initiative.

“Lawmakers vote on legislation that can have major impacts on ratepayers,” Dodge said.