DULUTH -- The Minnesota Vikings stadium, MNsure and mining were among the topics at Tuesday morning's debate between Gov. Dayton and Jeff Johnson, the Republican who wants his job.

The third debate of this race, at the Duluth Playhouse, was also the first to feature only Dayton and Johnson. The debate's organizers at the Duluth Chamber of Commerce did not invite Independence Party candidate Hannah Nicollet to participate, making it the first gubernatorial debate in years not to feature a major third-party candidate.

It allowed Dayton and Johnson to turn more sharply toward each other. The debate never got ugly, but both candidates got in a few solid hits on his opponent.

"I don't recall ever calling you a 'wacko,'" Dayton said to Johnson, after the Republican said Dayton had called him both a wacko and a huckster. Dayton didn't take issue with the second part.

"I do think hucksters are people who promise things unrealistically for selfish advantage," Dayton said.

This exchange came during a discussion of the proposed PolyMet copper and nickel mine near Hoyt Lakes on the Iron Range. Johnson charged that Dayton's administration purposely prolonged the environmental review process in order to kill the project.

"This governor is beholden to what I would call some pretty extreme environmental groups who don't want to see any mining in this state," Johnson said. He argued that the only way to ensure the project goes ahead is to elect him.

The PolyMet proposal has generated plenty of controversy in northeastern Minnesota, sparking conflicts over the job opportunities versus the potential that contaminated runoff from the facility could make its way into Lake Superior.

Backers have been seeking state approval for nearly a decade. That stretches back further than Dayton's, and he said it's taken too long. But he said to short-circuit the environmental review now, in its final stages, would be irresponsible.

"We need to be able to tell Minnesotans what they can reasonably expect with this undertaking," Dayton said.

There are two more scheduled debates in this race: Oct. 19 and Oct. 31, both in St. Paul.