Democratic U.S. Sen. Tina Smith and Republican Karin Housley debate in front of 300 people Thursday night at Hamline University in St. Paul. (Associated Press/The Minnesota Star Tribune)

In their first debate, Democratic U.S. Sen. Tina Smith and GOP state Sen. Karin Housley on Thursday clashed over issues ranging from health care and immigration to the nation's partisan divide.

Both agreed, however, that PolyMet's copper and nickel mine, which the state said earlier Thursday can proceed, would help the economy of northern Minnesota.

"Mining is not only part of the north country's past, but it's also part of its future," Smith said. "It's about time," Housley said of the decision.

Both also condemned the murder of journalist Jamal Khashoggi by Saudi Arabia and that country's war in Yemen. And they agreed that human activity led to climate change and said they support renewable energy sources.

The crowd of more than 300 at Hamline University in St. Paul seemed evenly divided. The two were interrupted frequently by applause, jeers, hissing and derisive laughter.

Health care and immigration, issues at the forefront of campaigns across the country, were points of contention.

Asked how she would make health care more affordable, Housley said Smith supports single-payer, government-run coverage and that her time living in Canada proved to her that it wouldn't work. Competition is essential, she said.

Smith said she already has proposed legislation to crack down on drug companies that pay makers of generic versions to keep them off the market. She also proposed allowing Medicare to negotiate for lower drug prices. To expand rural coverage, she suggested training doctors and nurses to work in those areas and expanding telemedicine.

In response, Housley spoke directly to Smith, noting that the senator has had almost a year to tackle the problem. "There's a lot of talk, talk, talk and nothing's getting done," she said.

Smith criticized President Donald Trump's plan to send thousands of U.S. troops to the southern border, while Housley suggested that her opponent supports "open borders" and allowing entry for Central American migrants who are making their way to the U.S.

Smith called for "comprehensive, common-sense" changes to immigration policies, including better security and allowing newcomers to have a path to citizenship.

Another question focused on Trump's decision to walk away from some international trade agreements. Housley supported the president's policies and declined to answer a question about whether she would have voted to withdraw from the Trans-Pacific Partnership.

Smith said every deal must be evaluated on whether it would create opportunities for Americans. The TPP, she said, did not meet that standard.

The debate also highlighted differences between the candidates on gun regulations, the U.S. withdrawal from the Iran nuclear deal and its exit from the Paris climate accord.

Smith said she backs universal background checks for gun purchases, but added, "I respect the tradition of gun ownership … that is such a part of Minnesota's culture." Housley focused on the allocation of funds to help keep schools safe from gun violence and called herself "a proud supporter of the Second Amendment." The solution, she said, "is not to penalize our lawful gun owners."

A question about the political environment prompted Smith to say voters are "so tired of this division and the politics of blame." Housley responded by saying that Smith opposed the Supreme Court nomination of Brett Kavanaugh without giving him a chance. "That's what we want to get rid of," Housley said. "That's extremism."

"I put Minnesota first when I made that decision," Smith said, adding that Kavanaugh's past rulings had been "outside the mainstream."

The intensity of the debate, which was sponsored by WCCO Radio, reflected the closeness of the contest. A Star Tribune/MPR News Minnesota Poll conducted Oct. 15-17 found a single-digit margin between the two candidates. Smith led 47-41 percent. They'll debate again Sunday on MPR.

The winner of the special election will complete the final two years of the term of Democrat Al Franken, who stepped down in January amid accusations of sexual misconduct.