U.S. Sen. Susan Collins and Democratic challenger Sara Gideon clashed over health care, money in politics and other issues during the final Senate debate Thursday night.

Collins, the Republican incumbent, repeatedly stressed her seniority and her work to address the COVID-19 pandemic over the last few months while Gideon, speaker of the Maine House of Representatives, tied Collins to Senate Majority Leader Mitch McConnell and said that as long as a Republican majority remains in the Senate little progress will be made on issues that matter to Mainers.

The race also features two independents, Lisa Savage, who emphasized her support for Medicare for All and brought in a Black Lives Matter activist to make her closing statement; and Max Linn, who said he will offer voters a change from the party candidates and the millions of dollars in advertising that comes with them.

Maine’s Senate race is among the most expensive and closely watched in the country, with more than $100 million raised so far when including money from outside groups. Several polls have shown Gideon with a slight lead on Collins.

The debate, hosted by News Center Maine and moderated by Pat Callaghan, was held virtually because Collins is in Washington, D.C. with the Senate in session. Callaghan opened the debate asking Collins why she supports McConnell when he has blocked consideration of further COVID relief bills and rushed through the Supreme Court nomination of Amy Coney Barrett.

Collins said she supports another COVID relief package and that a vote this week on her bill to extend the Paycheck Protection Program was just three votes short of the 60 needed to pass.

“I disagree with his position on having negotiations continue and a bill brought to the floor before the election, I think that is important,” Collins said. “Obviously I’m not going to agree with any leader all of the time, but I don’t hesitate to make my disagreements known.”

Callaghan then asked Gideon how she would act if the Democratic party controlled the Senate. Gideon said voters can look at her record in the Legislature and expect her to continue leading on issues such as climate and health care, but then turned back to the question of Collins’ support for McConnell.

“This gets to the very crux of what is happening here, because Mitch McConnell will continue to be the Senate majority leader as long as Susan Collins is in the Senate, and that means all the issues we care about, whether health care or the judiciary, will continue to be at risk,” Gideon said.

Among the issues the four candidates were asked about were ranked-choice voting, infrastructure and health care. All said that barring any malfeasance they would accept the results of the ranked-choice election, though Collins said she thinks a run-off allowing everyone to vote twice would be more fair.

Asked whether the country can afford a major transportation infrastructure bill, Gideon said it may be one area where she and Collins agree. Gideon said she believes the country does need infrastructure investments in things like roads and bridges, as well as broadband internet. And, she said, investments must be done in a way that addresses climate change and boosts renewable energy projects.

Collins, meanwhile, pointed to her work as chair of the Senate’s transportation appropriations subcommittee and said she has brought more than $740 million to Maine for sea ports, bridges and other infrastructure. She said a major infrastructure package is needed and should address the need for broadband.

Savage, who supports a Green New Deal, said she doesn’t think the United States can afford to not address infrastructure and do so in a way that addresses the climate crisis.

“Public transportation is a major way to cut down on our greenhouse gas emissions while still allowing people to get to work and get to school,” Savage said. “Investing in these kinds of systems is long overdue.”

Linn, meanwhile, said infrastructure is an area where he is strongest.

“The biggest threat to our state and our country is sending the same career politicians back to Washington again and again hoping for change,” Linn said. He said neither Gideon or Collins will have much say in Washington and real change, including on infrastructure, would come from an independent.

Collins again highlighted her work on the appropriations committee in response to a question from Callaghan about whether the possibility that she might chair the committee if re-elected would make a difference for Maine.

But Gideon said if Collins does become chair of the appropriations committee it would mean McConnell remains the Senate majority leader.

“Let’s remember what Mitch McConnell said when we last had a Democratic president,” Gideon said. “He said, ‘Let’s make it our mission to make this a one-term president,’ not ‘Let’s make it our mission to make progress on the issues that matter to people.’ ”

Collins rebutted that while she is in Washington working, Gideon has “done absolutely nothing” since mid-March to respond to the COVID crisis.

“Sen. Collins wants to continue to deflect. It has been six months since the Senate has been able to pass any COVID relief,” Gideon said.

Collins also hit Gideon on the issue of money in politics, saying that Gideon has “said one thing and done another” when it comes to taking corporate PAC money and money from drug and insurance companies. But Gideon said she didn’t hesitate to take on drug and insurance companies in the Legislature, and that she has pledged to not take donations from corporate PACs in the Senate race.

“That’s not what we have seen you do, Sen. Collins, where you have taken $6 million from corporate PAC’s and then done the bidding of those industries,” Gideon said.

All four candidates also differed on the issue of health care, although all said they believe health care is a human right. Linn, who supports a hybrid health care system with both private and government options, said universal health care would create a bankrupt nation. “Maine has a chance to send a message and we can do it with a vote for an independent,” Linn said.

Savage, meanwhile, supports Medicare for All including dental, vision, hearing and mental health care. Collins said lowering the cost of health care is key, including more transparency so people can compare prices, lower prescription drug costs and accessibility, including expanded telehealth in rural areas.

Gideon said she believes an expanded public option is necessary, but she doesn’t want to eliminate private insurance if people want to retain their existing coverage. She also criticized Senate Republicans for a federal lawsuit that seeks to overturn the Affordable Care Act. “There is by Sen. Collins’ own admission no plan to replace it,” Gideon said. “We cannot afford to re-elect Susan Collins.”

Collins, meanwhile, said Gideon was misrepresenting her record. Asked later in the debate by Gideon whether she regrets a later 2017 vote that eliminated the individual mandate of the Affordable Care Act and now serves as the basis for the federal lawsuit that seeks to overturn it, Collins said no.

“I was the deciding vote to keep the Affordable Care Act in 2017 as you know and in fact the Democrats are using my arguments right now to defend the law before the Supreme Court, so I’m proud of my record,” Collins said.