On a slew of environmental issues, President Donald Trump and Democratic hopeful Joe Biden are opposites, from climate change to renewable energy.

But on one of Minnesota’s most pressing environmental concerns, opening the state to copper-nickel mining, the division isn’t quite as clear. Trump has boasted of opening up northern Minnesota to mining for minerals and copper. Meanwhile, Biden has been publicly mute on the subject.

Biden has not come out for or against either of the two controversial copper mines lined up for the state. His campaign did not respond to repeated requests to discuss the matter or even confirm that he has not taken a position.

The silence makes perfect sense, many stakeholders say, given the tightrope moderate Democrats walk between the DFL’s distinct labor and environmental wings, particularly in Minnesota’s northeast. And with Minnesota a key swing state in this presidential election — Trump narrowly lost it in 2016 — Democrats do not want to risk alienating voters in either camp. Nathaniel Rakich, elections analyst at Nate Silver’s Five­ThirtyEight political blog, calls the state “now one of the likeliest states to be the Electoral College tipping point.”

Interpretations of Biden’s silence on opening Minnesota to copper mining differ.

“If Biden is elected there will be no copper-nickel mining even though he’s not saying anything about it,” said Jennifer Carnahan, chairwoman of Minnesota’s Republican Party. “We know where he stands. He was in Obama’s administration for eight years.”

The Trump administration has pushed copper-nickel mining just outside the Boundary Waters Canoe Area Wilderness, reversing key decisions by the Obama administration to block it as too risky for the fragile ecosystem.

Other stakeholders are reading tea leaves on what a Biden presidency means for the copper mining industry’s advance in Minnesota.

“I certainly wish he would come out with a strong statement saying this is not wise at this time. I understand also why he hasn’t,” said Veda Kanitz, chair of the Minnesota DFL’s environmental caucus. “It’s a difficult topic. He does not want to be seen as someone who is anti-jobs. Of course, we know this is a false dichotomy.”

For the first time, the state DFL in September adopted a resolution for a moratorium on copper-nickel mining in Minnesota until it’s clear it can be done without great environmental costs. Kanitz said she thinks the move indicates the environmental wing of the Democrats is gaining strength.

Kanitz, a national delegate for Biden, said she is unconcerned about Biden’s silence because she’s confident that if he is elected, he will surround himself will people who will “side with science.”

Pro-copper mining DFLer Adam Duininck, director of government affairs for the North Central States Regional Council of Carpenters, said he’s also not worried by Biden’s silence. The union, which supports both copper mining projects, recently endorsed Biden.

“He knows labor is a valuable member of the Democratic Party. He wants to be open to projects that are going to create jobs,” Duininck said.

Steve Giorgi, executive director of the Range Association of Municipalities and Schools, an Iron Range institution that strongly supports copper mining, agrees.

As Giorgi sees it, Biden has signaled his more moderate environmental position. Biden recently decided not to embrace a ban on fracking, he noted, and did not fully embrace the Green New Deal, instead developing his own $2 trillion clean energy plan. Those moves, Giorgi said, “give people the optimism that he’s not going to take a direct assault on copper-nickel mining in Minnesota.”

Cynthia Rugeley, head of the Political Science Department at the University of Minnesota Duluth, said Biden hasn’t addressed copper-nickel mining because he does not need to in this election.

“If it was any other candidate than Trump, it would probably be different,” she said.

Biden, Rugeley noted, will have strong sympathy for arguments on jobs: “He’s very much pro labor, all the way through his bones.”

Meanwhile, quoting unnamed sources, Reuters reported that Biden campaign staff have privately told U.S. miners that Biden “would support boosting domestic production of metals used to make electric vehicles, solar panels and other products crucial to his climate plan.”

Bruce Richardson, a spokesman for PolyMet Mining Corp., majority owned by Switzerland-based Glencore, said he’s unaware of those conversations.

“We have not had any conversations with anyone from Biden’s camp,” Richardson told the Star Tribune. “I can’t speak for Glencore.”

Environmental groups see equally strong signals that a Biden administration could thwart the industry’s advance in Minnesota.

Biden’s clean energy climate plan pledges “banning new oil and gas permitting on public lands and waters.” In August, he announced he is opposed to expanding mining uranium around the Grand Canyon National Park, calling it a sacred “national treasure” and saying that uranium mining pollution threatens the health of people in the Navajo Nation.

He has also pledged to block the proposed Pebble Mine, a copper and gold mine in Alaska’s Bristol Bay watershed, where vast numbers of Pacific salmon spawn and rear.

Those moves have Becky Rom, Ely area resident and head of the Campaign to Save the Boundary Waters, feeling optimistic.

“It tells me his values,” Rom said. “Biden cares about these really important public lands, these iconic places.”

“I’m personally convinced that at the end of the day the Biden administration will do the right thing and protect the Boundary Waters.”