PORTLAND, Maine (AP) — Thanks to a proposal for $258 million in incentives, Democratic Gov. Janet Mills announced Thursday she’s giving her support to a 145-mile transmission line that would supply hydropower from Canada to electricity consumers in Massachusetts.

The $1 billion New England Clean Energy Connect will reduce the region’s reliance on fossil fuels and reduce electricity costs in the region at no cost to Mainers, Mills said.

“I ran for the office of governor with a promise to reduce our reliance on fossil fuels, to address our carbon footprint and to accept the challenge of preventing and mitigating climate change,” the governor said in a statement. “We cannot afford to do nothing.”

The Central Maine Power project would provide a conduit for hydropower from Canada to reach Massachusetts to meet its green energy goals.

On Thursday, CMP filed a document with state regulators with additional incentives including $140 million for rate relief for retail customers, $50 million for low-income energy customers, $15 million to subsidize heat pump purchases and $15 million for electric vehicle charging stations.

The new incentives were enough for Mills to authorize her energy office to support the proposal. Also signing on to the deal was the Conservation Law Foundation.

Supporters say the project would provide electricity for 1 million homes and drive down electricity rates for all of New England.

Critics say it would spoil vast tracts of wilderness and harm Maine’s homegrown green power initiatives, like solar and wind power. The Natural Resources Council of Maine contends the project has failed to show that there would be a reduction in greenhouse emissions.

The New England Clean Energy Connect calls for building a high-voltage power line from Mount Beattie Township on the Canadian border to the regional power grid in Lewiston.

Much of the project calls for widening existing corridors, but a new swath would have to be cut through a 50-mile segment of wilderness in western Maine. The utility already agreed to route the lines underneath the Kennebec River Gorge because of concerns raised by environmentalists.

Central Maine Power’s proposal was selected by regulators in Massachusetts after New Hampshire officials pulled the plug on the controversial Northern Pass project.