PORTLAND (AP) — The Sierra Club is endorsing Democrat Mike Michaud over independent Eliot Cutler in the governor’s race, announcing a yearlong education effort that will likely be backed by spending from the national group with a goal of preventing Republican Gov. Paul LePage from winning a second term, the group said Monday.

The earliest-ever gubernatorial endorsement by Sierra Club Maine reflects how lines are being drawn earlier than ever as candidates and their supporters try to shape the three-way race.

“We’d like to rally our troops early,” said Melissa Walsh Inness, political team chairwoman for the environmental group with 8,000 members and supporters across the state.

Four years ago, there were a dozen Republican and Democratic candidates and the field wasn’t settled until the June primaries. This time, the three-way race is already set.

The race presents some stark contrasts on environmental policy. LePage, for example, opposes wind energy because it’s too expensive, while Michaud wants to boost green energy. In fact, Michaud wants to cut reliance on heating oil in half — from today’s level of 70 percent to 35 percent — by the year 2030.

Cutler has his own environmental record that dates to his days helping Sen. Edmund Muskie shape the Clean Air Act and the Clean Water Act and later environmental work as an attorney. Both Michaud and Cutler say a clean environment is key to Maine’s future and economic development.

The Sierra Club’s endorsement came down to Michaud vs. Cutler, and the Sierra Club made it plain that LePage wasn’t in the mix. LePage didn’t even bother to fill out a survey or responding to a request for an interview, the environmental group said.

“We are devoting all of our resources to replacing Paul LePage with a pro-environment governor,” said spokesman Glen Brand.

Brent Littlefield, LePage’s senior political adviser, said the administration levied the second-largest environmental fine in Maine history for an oil spill, underscoring the administration’s environmental commitment and providing proof that the “endorsement is about liberal politics, not protecting Maine’s environment.”

Ted O’Meara, spokesman for Cutler, said the Sierra Club’s endorsement came as no surprise because it generally backs Democratic candidates.

Michaud, for his part, said he first ran for office in the Legislature more than 30 years ago to clean up the Penobscot River, which was being polluted by the paper mill where he worked.

“I’ve been fighting for commonsense environmental policies ever since then. Back then I learned an important lesson, both the environment and business can co-exist. It’s in everyone’s best interest to protect our natural resources,” he said.