A lobbying group promoting a controversial mining project in Minnesota is working with an ad firm that primarily buys ad time for Democratic candidates.

The group, Mining Minnesota, is a lobbying organization with six registered state lobbyists. Its executive director, Frank Ongaro (also its designated lobbyist) was previously the president of the Iron Mining Association of Minnesota, according to his LinkedIn page. The group lists a number of “industry supporters” on its website, from engineering and energy companies to law firms and staffing services.

Probably the two most significant organizations on that page are PolyMet and Twin Metals (both of which have members on Mining Minnesota’s board of directors). These are mining companies who are both seeking to build controversial new copper and nickel mines in Minnesota. The mines would extract the metals from sulfide ore, which creates harmful sulfuric acid when exposed to air and water; environmentalists worry this could leak into the water supply through “acid mine drainage.” The sulfides can also create methylmercury, the most toxic form of mercury. According to Al Jazeera America, the region the mines would be built in contains “the nation’s most irreplaceable freshwater resources,” such as Lake Superior, which “holds 10 percent of the world’s fresh surface water.”

Mining Minnesota spent at least $42,000 in ads in Minnesota and Wisconsin in November. What’s interesting about that is the firm that placed the ads for them. Canal Partners Media is a big vendor for Democratic candidates and issue campaigns, with offices in D.C. and Georgia. During the 2014 cycle, they were paid $44,949,240 by 48 candidates and issue campaigns, including Michelle Nunn, Mary Landrieu and the United Steelworkers, according to OpenSecrets.org. (Bear in mind, ad-buying firms also pay the networks they’re running ads on for the airtime, so the firm didn’t make $44 million itself; it keeps a small commission of that total).

Mining Minnesota hasn’t put any of its ads online, as far as we can tell (if you can find them, please send them to us!), but it did run this radio ad in June. There is currently no online system of disclosures for radio ads.

To understand why it’s strange that Canal is working for this group, let’s look at what the group is after. PolyMet, one of the companies behind Mining Minnesota, is seeking permission to build a mine near Hoyt Lakes, MN, in Superior National Forest. PolyMet claims it would create 360 full-time, “middle-class, living-wage” jobs, and a report produced by the University of Minnesota-Duluth’s Labovitz School of Business and Economics — on behalf of PolyMet and state agencies — said the mine could lead to 600 “indirect” jobs.

Twin Metals’ proposed mine, an underground mine near Ely, Minn., is “at least five years behind the PolyMet mine in the approval process.” But PolyMet is getting pretty close to the finish line. The 3,000-page Environmental Impact Statement (EIS), 10 years in the making, was released on Nov. 6. It found that PolyMet would be able to contain the potential pollution from the mine, the main concern being that wastewater (containing the harmful sulfides) from the mine would contaminate the water supply, either through seepage or the collapse of containment systems. Environmental groups aren’t buying that conclusion. The environmental group Earthworks says that every single one of the 14 copper sulfide mines in the U.S. has experienced “pipeline spills or other accidental releases,” and that in some cases the water pollution will continue “in perpetuity.”

The release of this report was followed by a public comment period, which ends on Dec. 21, extended from Dec. 14. (A previous comment period on the environmental review saw more than 50,000 comments; Mining Truth, a group opposed to the PolyMet mine, says 98 percent were opposed to the project.) The Department of Natural Resources will issue its final decision in February, and permits could be issued as soon as spring 2016. Gov. Mark Dayton, a Democrat, has said this “will be the most momentous, difficult and controversial decision I’ll make as governor.”

This means we’re at a crucial lobbying moment for the mining companies. And it seems like Mining Minnesota’s push might already be working — the governor just announced on Dec. 8 that no study into the PolyMet mine’s impact on human health will be conducted, a move condemned by Minnesota physicians and public health officials, who are particularly concerned about an increase in mercury in the water supply.

So this is something of an incongruous client for Canal, who normally work for Democratic candidates and causes (including the Minnesota Democratic Farmer Labor Party). In May, they purchased ads on behalf of Friends of the Earth for a spot about the Trans-Pacific Partnership (TPP), which they oppose on environmental grounds. (We can’t be sure if it’s the same one, but this ad from Friends of the Earth’s YouTube page, uploaded in May, criticizes Rep. Earl Blumenauer, D-Ore., for his vote on the TPP fast-track). Canal also bought ad time for an Environmental Defense Fund group ad attacking GOP Senate candidate Cory Gardner in Colorado, and it has worked for pro-environment candidates, such as Julia Brownley, D-Calif., who was endorsed by the League of Conservation Voters.

We should also note that Mining Minnesota isn’t the only group lobbying on this — Mining Truth has also bought ad time opposing the project. It paid $9,830 for ads in June and July; it also ran ads in October and November, but the stations the ads ran on didn’t post the invoices for them and didn’t provide us with them when we asked. Their ads were placed by a group called The New Media Firm, who have an extensive progressive client list, including Sen. Sherrod Brown, D-Ohio, Common Cause, EMILY’s List and many unions.

Unfortunately, Minnesota’s state campaign finance disclosure data is extremely out of date — the state only has independent expenditure data through December 2014, so we have no idea how much is being spent by either group on any other kind of activity.

This is a group that’s known for placing ads supporting Democrats (generally the more pro-environment party) and which has worked with environmental groups in the past. Why is it now working for a coalition of mining companies loathed by environmental groups? We reached out to Canal to ask about this curious arrangement, and we haven’t heard back.