A letter calling on Rep. Rick Nolan, D-Minn., to run for governor next year is being circulated to more than 1,000 members of Minnesota’s Democratic-Farmer-Labor Party.

The letter, signed by DFL activists, lawmakers and lobbyists, warns that Minnesota could become like Republican Gov. Scott Walker’s Wisconsin, the Star Tribune of Minneapolis reported.

The letter notes how Nolan has been able to win close races — in his most recent, he beat businessman Stewart Mills in a rematch of 2014 in Minnesota’s 8th District, which went for President Donald Trump.

Nolan said in January he is considering running.

Environmentalists plan to oppose Nolan because of his support of copper nickel mining and other environmental issues.

State Auditor Rebecca Otto, Rep. Erin Murphy and St. Paul Mayor Chris Coleman have declared they are running. Lt. Gov. Tina Smith, U.S. Rep. Tim Walz, Attorney General Lori Swanson and several others have been mentioned as other possible DFL candidates. 

The letter is signed by a few state legislators and the former president of the Minneapolis City Council. But Nolan could face opposition from environmental activists for his support of copper nickel mining.