Democratic Rep. Rick Nolan and his GOP challenger Stewart Mills sparred over guns, Obamacare, tax reform and even engaged in a little class warfare at an early morning debate in Duluth.

The Eighth Congressional District fight is Minnesota's hottest race. Nolan is defending the seat he's had for just one current term against Stewart Mills, a 42-year-old political nascent and scion to Mills Fleet Farm.

Before it started, the debate had the trappings of being a little sleepy. It started at 8 a.m., the candidates sat down in a coffee table format, and the third-party candidate Ray "Skip" Sandman also participated, slowing down the fiery dialogue between Mills and Nolan.

In spite of all that, Mills and Nolan drew sharp contrasts, lashing out at each other's differences on reforming the Affordable Care Act, copper-nickel mining and tax reform.

Nolan took multiple swipes at Mills' net worth, which is between $47 million and $153 million, according to personal financial disclosures.

"I know what it's like to build a business from the bottom up and create jobs ... but if we want to rebuild this middle class we need to get away from this trickle down theory," Nolan said, when asked about tax reform. "Stewart, you made more money ... sitting here in an hour and a half ... than the minimum wage earner will make in a week ... The rich are getting richer and the poor are getting poorer."

Mills defended his company and his family, saying they work hard and play hard and building the business meant it "may get a little bit bloody sometimes." After noting the IRS has been "weaponized against the American people," Mills said he wanted to flatten the tax code to be friendlier to Main Street.

Throughout the debate, Mills referred to Nolan as "Representative Nolan' while Nolan called the third-party candidate "Mr. Sandman" and Mills "Stew" or "Stewart."

On guns, Mills touted his endorsement by the National Rifle Association and said Nolan's positions on banning semi-automatic weapons and limiting magazine capacity were not in line with the District's values.

"We need to enforce the laws we currently have rather than making up new ones," Mills said.

Nolan flared, "I don't need a semi-automatic rifle to shoot a duck," he said. "Maybe you do, maybe you should spend more time on your shooting range."

Polls show the Mills/Nolan race within a couple points of each other and national political forecasters call it a "toss-up." The Eighth Congressional District is politically whimsical, electing Republican Chip Cravaak in the 2010 Tea Party sweep and then elected Nolan two years later.

Nolan has consistently out-fundraised Mills, even though Mills has donated more than $150,000 of his own money to his campaign. Nolan's camp said yesterday the incumbent brought in $641,000 since July -- his best quarter to date. Mills' campaign declined to say how much the candidate raised in the third-quarter Tuesday.

Mills said he supported both the construction of the Keystone oil sands pipeline and the Sandpiper line, which will deliver crude from North Dakota to an existing terminal in Wisconsin. He said Nolan has been inconsistent in his support for the new lines.

"We're not quite sure where Rep. Nolan is," he said. "He can say he's for it right now, but where's he going to be tomorrow?"

Nolan said he also favored both projects as long as they followed environmental rules. Nolan said he grew up at a time when "condoms" and "turds" polluted rivers and acid rain was wreaking havoc on forests.

"I submit that we must be compliant with good, sound, environmental rules and regulations and we have the technology to move forward with mining," he said. "We need to protect our environment as well."

On Obamacare, Mills said he favored a health care plan that protects people with pre-existing conditions but supports reforming it, allowing people to buy and sell plans across state lines and tort reform.

Nolan, who favors a single-payer system, snapped, "Now Mills is saying he supports many of the things in the ACA and then he is saying he wants to repeal it. Talk about double-speak ... It's starting to smell like a barn on a warm Sunday afternoon."