It was likely their final face-to-face showdown in a race with potentially major national implications.
Over the hour, Republican U.S. Sen. Susan Collins and Democrat Troy Jackson disparaged each other's records, portrayed the other as beholden to political interests far from Maine and drew laughs from the audience with their sharp barbs. At one point, Jackson even told Collins to "shut up" after she quipped that a protester obviously came from his camp.
But they occasionally agreed on issues, such as about the pernicious effects of the "dark money" that is pouring into Maine to attack and prop up both candidates.
Here are a few key takeaways from Thursday night's debate co-sponsored by Maine Public, NEWS CENTER Maine and the Portland Press Herald.
Trump's shadow looms large
As he'd done throughout their three previous joint appearances, Jackson sought to portray Collins — a 30-year Senate veteran — as a key cog in a Republican majority in Congress that he says refuses to stand up to what he believes is a dangerous president.
"They will not stop Donald Trump and I do think our democracy is risk," Jackson said before accusing Trump of trying to suppress the vote in November. "Donald Trump is trying every trick in the book to keep power. And we've already seen what he will do on Jan. 6 when he led an insurrection."
And he repeated one of his favorite statistics — that Collins allegedly votes with Trump 96% of the time.
"The reality is that 100% of the time, when Donald Trump needs her, Susan Collins is going to be there," Jackson said. "The votes that she throws away are managed votes that she already knows the outcome."
As she's done in previous debates, Collins accused Jackson of cherry-picking a number from a study that only examined about one-third of the votes that have been taken. The real figure, she said, is about 72%. And Collins pointed to years of analysis consistently showing her the most or one of the most bipartisan senators from either party.
"He is going to be an automatic vote for the Democratic position no matter what," Collins said of Jackson. "We have lost a lot of the centrists and one of the reasons is we need people who will work across party lines."
The 'Oh shut up' moment
It's probably a safe assumption that both candidates have wanted to say this to the other at some point (or lots of times) during the three previous tense debates. But it took an unexpected to disruption to bring it out.
The brief scene began when an audience member began shouting at Collins about the environmental impact of data centers as she started answering a question on an entirely different topic.
"So this is obviously one of Troy's supporters," Collins said, leaning slightly into the microphone.
"Oh shut up," Jackson shot back. "I did not ... I don't even know that kid."
"Oh right," Collins said sarcastically.
Just before Collins' initial remark, Jackson had been frowning and shaking his head in the direction of the protester. And from the audio and video, it seems like Jackson's "oh shut up" was more flippant than mean-spirited. The two rivals even seemed to exchange snarky smiles before the debate quickly resumed without future disruption.
Not surprisingly, the Senate Leadership Fund — one of the super PACs spending millions of dollars to support Collins — called attention to Jackson's statement in an email blast.
The protester was later identified as Henry Elgie, a 19-year-old Bowdoin College student. A press release from the Sunrise Movement — a self-described "youth movement to stop climate change and create millions of jobs in the process" — said in a press release that Elgie was part of a pattern of students confronting politicians on the campaign trail.
Some new issues and divisions
Despite this being the fourth debate, the two panelists — Maine Public chief political correspondent Steve Mistler and NEWS CENTER Maine host and political reporter Phil Hirschkorn — managed to get the candidates to weigh in on some new issues.
In some cases, they almost agreed.
Both Jackson and Collins said they were opposed to so-called "dark money," which is when political donors hide their contributions by giving to organizations that don't have to disclose their sources, such as politically active 501(c)(4) nonprofits. According to Mistler, Collins and Jackson have benefited from at least $75 million in dark money spending so far.
Collins said she has supported sweeping campaign finance reforms in the past that did not pass constitutional muster.
"I still think that there are reforms that could be made, and one of them is full disclosure of everyone who is contributing," Collins said.
"I'm 100% for overturning Citizens United," Jackson said, referring to the Supreme Court decision that opened the door to unlimited spending on campaigns and, by extension, the creation of super PACs. "I mean, billionaires have bought Congress and everyday people can't afford to buy them back."
On the issue of a guns, Collins reiterated that she would support a ban on so-called bump stocks that allow semi-automatic guns to function more like a machine gun and would support "reasonable" limits on magazine capacity. She also said would be "open" to increasing the age to purchase an assault weapon from 18 to 21.
Jackson said he opposes increasing the minimum age. But unlike Collins, he would support a ban on the purchase of assault weapons — but would not support taking them away from people who already own them.
But the rivals disagreed sharply on whether the Supreme Court should be expanded.
Some progressives are pushing to add justices to counteract the court's 6-3 conservative majority. Jackson supports the idea and also called for term limits on justices and ethics reforms.
"We have the best Supreme Court that money can buy right now and I think that has to be turned over," Jackson said.
But Collins said adding justices would amount to political interference.
"It's inconsistent with the whole idea of the Supreme Court being insulated from politics ... that would make it a total political body," Collins said.
The last time Congress added seats to the Supreme Court was in 1869.
