Gov. Janet Mills has vetoed legislation to temporarily ban the development of large-scale data centers in Maine.

The bill passed through the state Legislature with bipartisan support earlier this month. It would have enacted an 18-month moratorium on new data centers using more than 20 megawatts of power. If enacted, the law would have been the first of its kind in the U.S.

But the governor had asked for an exception to allow a $550 million facility planned in Jay. But an amendment to the bill that exempted the Jay project was defeated in the Legislature.