DFL Gov. Mark Dayton’s reputation as an environmentalist is being tested by an intensifying political clash between conservationists and another core constituency of his — organized labor.

As Dayton lays the groundwork for his re-election campaign next year, he is striving to strike a delicate balance between the demands of environmentalists he feels a deep kinship with and his devotion to the labor movement that played a crucial role in his 2010 election.

“Sound economic growth and environmental protection are complementary,” Dayton said in an interview last week. “But a lot of people view them as conflicting ... which makes it very, very difficult.”

Dayton has already been embroiled in several divisive jobs-vs.-environment conflicts, and has made decisions that rattled both sides. Dayton’s selection of Department of Natural Resources Commissioner Tom Landwehr angered some Iron Rangers who grew skeptical of his commitment to job creation. Dayton later agreed to a compromise that allows the booming frac sand mining industry to operate closer to trout streams than environmentalists wanted, but requires a permit to do so. Two years ago, Dayton bucked many environmental groups when he backed a much-criticized, four-lane bridge over the St. Croix River near Stillwater that is one of the largest projects of its kind in the state in years.

Now, new challenges in energy production and mining are putting Dayton in a difficult political landscape, with both sides pressing hard on some of the most polarizing issues in the state.

“It is going to be tricky for him to navigate between two constituencies he will need to come out for him in a big way,” said Aaron Klemz, a spokesman for Friends of the Boundary Waters Wilderness. These environmental battles “expose a lot of fissures in the DFL.”

The latest flare-up in this long-simmering feud has converged in a new mining proposal in the Iron Range.

PolyMet Mining Inc. wants to pull copper, nickel and other precious minerals from an abandoned mine near Hoyt Lakes, a $600 million proposal that some see as a way to revive the region’s mining industry.

Labor groups strongly back the proposal, which would bring hundreds of high-paying jobs to a community that has struggled after the mine closed more than a decade ago. The potential downside: It would usher in a type of mining known for damaging water systems and place it near the Boundary Waters Canoe Area Wilderness, potentially affecting Lake Superior. Joining the fight are some of the state’s wealthiest and most politically connected environmental groups — including some backed by Dayton’s former wife, Alida Messinger.

Many advocates on both sides see the issue as the biggest showdown between labor and environmentalists in years.

“Most of the people who are really engaged on this copper-nickel mining have already made up their minds one way or the other and are not likely to be persuadable on anything else,” Dayton said.

Many project backers say the stakes could not be higher as they look to re-energize the economy in the northeastern corner of the state. Squashing the project, they say, would be a tough blow and signal that environmentalists have too strong a grip on the Dayton administration.

‘We built America’

“There’s a lot more Rangers than environmentalists,” said former DFL state Rep. Tom Rukavina, now an aide for U.S. Rep. Rick Nolan, D-Minn. “We built America and won two world wars for this country. If they can’t figure that out, then I guess they have a lesson to learn.”

Dayton has nurtured strong ties with the environmental community. While in the U.S. Senate, he opposed oil drilling in the Arctic and pushed for tougher oil and gas smokestack regulations. In recent days, he talked about the need for more clean energy initiatives.

“I trust him,” said Paula Maccabee, an attorney for WaterLegacy, an environmental group fighting to stop the PolyMet project. “What the governor has told me is that he is not going to prejudge the issue and wait to see the facts and the science. I take him at his word.”

But Dayton has confounded environmentalists, too. Recently, the governor said he would like to abolish the federal Environmental Protection Agency, citing seven years of delays as the office reviews the PolyMet project. Environmentalists argue the EPA often plays the role of a crucial backstop against well-connected mining and energy companies.

Two years ago, Dayton stunned environmentalists when he stood with Republican U.S. Rep. Michele Bachmann to support the new bridge over the St. Croix River near Stillwater. In doing so, he bucked many in his party, including former Vice President Walter Mondale, who co-authored the clean rivers measure that was a last major obstacle for the project. Dayton joined with Republican Wisconsin Gov. Scott Walker to write a letter asking Congress to exempt the bridge from Mondale’s U.S. Wild and Scenic Rivers Act.

“I am a strong environmentalist, but I am also strongly pro-jobs.” Dayton said. “I have a good common-sense perspective on the balance that has to occur.” Environmental protection, he said, “is a very, very important responsibility of mine as governor and as a citizen.”

Dayton has had a complex relationship with Iron Range DFLers and labor organizations, too. Many there speak fondly of him, his frequent visits to the area and his years heading economic development for former Gov. Rudy Perpich, an Iron Range legend. Privately, some say they worry that Dayton’s former wife wields too much influence on him and that some of his commissioner picks tilt toward the environmental extreme. They worry that state delays may stall other mining projects on the Range, choking its economy.

Dayton said his former wife has no influence on his decisions on policies or appointments.

“She has her opinions and she expresses them infrequently, but only on matters that are of great importance to her, like nuclear waste disposal and nuclear power,” Dayton said. “I respect Alida enormously and I certainly listen to her, but I am not swayed by her opinions.”

The governor said he has not discussed the mining issue with Messinger.

“She would like to broach it, but at this point I have said it is premature,” Dayton said. “I have to figure out how to respond to people on both sides who want to talk to me.”

PolyMet officials are trying to persuade state and federal regulators that they have the technology to prevent environmental damage to surrounding areas. A crucial decision for Dayton’s administration on whether the project moves forward could come next year, as his re-election campaign is in full swing.

Some of his biggest backers on both sides are keeping a close eye on the process.

“We are watching our bobber and they are probably watching theirs,” said Harry Melander, president of the Minnesota State Building & Construction Trades Council.

“I believe this is one of the few things that keeps the governor up at night,” said state Rep. Tom Anzelc, DFL-Balsam Township. “You can’t sugarcoat it at all. It is overlaid with immense political ramifications.”

Dayton knows his re-election chances, even his legacy, will rest in part on how he sorts through the environmental issues that are part of some of the state’s most promising economic developments.

“I certainly don’t want my legacy after one or two terms to be the contamination of the treasure that exists in that part of the state,” Dayton said of northeastern Minnesota. “So you weigh it all in the balance.”