The three candidates for U.S. Senate sparred on immigration, health care, gun control and more during a fast-moving debate Monday night.

U.S. Sen. Angus King, the incumbent independent, said he is running for re-election because he has seen a lot of “hope and heartbreak” over the past year, and he wants to address both.

He mentioned the opioid crisis and lack of care for veterans as challenges, but said, “there is hope, too.”

“I want to build on the positives,” King said during the debate hosted by NewsCenter Maine (WCSH/WLBZ). “This is not a time I feel I can walk away.”

Republican Eric Brakey, who is likely King’s biggest challenger, spent most of the debate attacking the senator, just as he did during a radio debate last week. Brakey’s closing statement Monday was no exception.

“I think we’ve gotten a rotten deal for far too long,” Brakey said before criticizing King for his ties to the energy industry. “We need to get Washington, D.C., out of our lives.”

Democrat Zak Ringelstein also tried to distinguish himself from King, but was far less combative than Brakey.

“I believe we can do better,” Ringelstein said. “If you believe the last 25 years have been good … you should vote for Angus King.”

Monday’s debate, moderated by anchorman Pat Callaghan, was the first televised debate of the campaign season for this race, and came eight days before Election Day on Nov. 6. Three more debates are scheduled for this week.

There has not been a lot of public polling in the race, but King appears to have a solid lead.

In an online poll of 500 likely voters released last week by the Portland firm Pan Atlantic Research, King had 57 percent support, compared with 29 percent for Brakey and 8 percent for Ringelstein, with 5 percent undecided. King also had a 64 percent favorability rating, the highest of any of Maine’s four members of Congress.

That poll shows the race has not moved much since August, when a Suffolk University survey showed King at 52 percent, Brakey at 25 percent and Ringelstein at 9 percent.

The Brakey campaign released the results of a poll question that the campaign paid for from the local firm Critical Insights, which showed a closer race. That poll of 600 registered voters had King at 41 percent, Brakey at 27 percent and Ringelstein at 7 percent, with 23 percent undecided.

King also has a major advantage in fundraising.

He has raised $5.4 million since January 2017, and has $2.3 million on hand for the last stretch of the race.

Brakey brought in $244,538 in the third quarter, for a total of $708,613. He has $110,646 on hand for the final weeks.

Ringelstein raised $34,783 in individual contributions in the third quarter, for a total of $212,125 for the entire campaign — an overwhelming majority of that from a candidate loan — and he has $116,000 on hand.

Both Brakey and Ringelstein went after King for his voluminous contributions from political action committees and the energy sector, where King has strong ties.

That, however, was the extent of their agreement.

Ringelstein, at one point, criticized Brakey sharply for recent anti-immigrant rhetoric. On Sunday morning, Brakey tweeted: “Why did California turn Blue? Why is Texas turning Blue? The left has failed at selling socialism to the American people for decades. We have rejected it. Their new strategy is mass importation of new voters to transform our political culture.”

“It’s disgusting that you’ve decided to go the way of Trump,” the Democratic candidate said before calling on Brakey to end his campaign.

Brakey, undeterred, said Ringelstein is the one polling in single digits.

Brakey later defended his views on immigration, and said he is tired of people like him being labeled racist for wanting strong borders.

King mostly stayed out of that fight. He acknowledged the immigration debate has become highly emotional. He said, with few exceptions, everyone is an immigrant and we should not be targeting people out of fear.

“But we can’t have open borders either,” he said.

King leaned more on policy details and specifics in his answers. Ringelstein’s answers were far more global. Brakey tried to tie everything back to King.

In one exchange, King listened as Brakey criticized him for voting too much with Democrats, and Ringelstein lamented King voted too much with President Trump.

There were many differences between the candidates both in style and substance. King, at 74, is older than both Brakey and Ringelstein — each in his early 30s — combined.

Brakey, a libertarian, offered market-based capitalist solutions to most questions. He praised the Republican tax cuts and deregulation.

Ringelstein, a Democratic socialist, supported universal health care and strict gun control.

King’s answers were less black and white. On foreign spending, he agreed cuts could be made to help balance the budget, but added, “We can’t just retreat from the world.”