The hardscrabble region has a long history of boom-and-bust economies and has fallen victim to cheaper steel imports that have forced USA producers to close area taconite mines and curb production.
"President Trump's comments fly in the face of 70 percent of Minnesotans who are opposed to this risky type of mining near the priceless Boundary Waters Canoe Area Wilderness, " said Doug Niemela, national campaign manager for the Campaign to Save the Boundary Waters, in a statement.
California, with seven times as many residents, is the only other state with that many districts rated the same way by the nonpartisan Cook Political Report.
Trump is also offering a full-throated endorsement of GOP congressional candidate Pete Stauber. "I couldn't tell. Needs a haircut". "Action needed to be taken to protect the USA steel industry and the jobs here on the Iron Range", he said. After launching his campaign in April, Pawlenty said he still voted for Trump in 2016 and supports the president's policies.
"The intensity and support for President Trump is as good as it was for him on Election Day", said Stauber, a former professional hockey player. "He's very, very popular in the 8th congressional district".
As the protesters were escorted out, Trump questioned whether one protesters was a man or woman.
The third, in southeastern Minnesota, doesn't have an incumbent running.
"These people", said Mr Trump, gesturing to the media at the back of the arena, "say, "He's given away so much". Power was restored before Trump arrived. Through March 31, he'd raised four times as much money as the closest Democrat. "He has a base out of the largest population center to build from and he will have an appeal on the Iron Range", he said.
Many at Trump's rally wore "make mining great again" caps, and he was handed one that he showed off to photographers.
The US president appeared in front of around 8,000 fans in Duluth where he played down the crisis that had threatened to envelope the White House as images of children being taken from their parents sparked global condemnation.
The activists held up signs and disrupted the event minutes apart as the president railed against illegal immigration.
Trump's trip to Duluth was an attempt to do just that. He raved about the economy and his tough new tariffs meant to create fair trade.
Minnesota has historically been a Democratic stronghold.
The president also raised the North Korea summit, calling it an "incredible success". His 2020 campaign manager is already reportedly targeting the state for the re-election race, along with another state Clinton won, Colorado.
Trump said his administration is "taking first steps" to open the Superior National Forest to mineral exploration.
"I truly believe that it will energize a lot of Republican voters in the state. and get people to start paying attention earlier than they normally would", Johnson said.
While Trump's roundtable and campaign rally are supposed to be focused on trade issues, the president is likely to talk about immigration and the controversy surrounding his administration's "no tolerance policy" to arrest anyone who illegally crosses the border.