BANGOR, Maine — Maine’s 2nd Congressional District could set U.S. Rep. Bruce Poliquin farther down a path to political stardom on Tuesday or provide for a Democratic win over an incumbent Republican congressman for the first time in Maine in the last 20 years.

The bitter rematch of 2014’s battle between the Oakland freshman and Democrat Emily Cain, a former state legislator from Orono, has been amplified by nearly $16 million in campaign and outside spending that barraged the district with more ads than any other House race through mid-October.

That shattered their own Maine congressional record of $6.7 million two years ago, signaling its increased importance on the parties’ national maps as Democrats look likely to narrow — but not steal — the Republican majority in the U.S. House of Representatives.

Since Cain’s loss to Poliquin, she has counted on the district returning to its Democratic roots in a presidential year, when the state hasn’t backed a Republican since 1988. But Republican Donald Trump has strongly battled Democrat Hillary Clinton to give the district toss-up status.

Here are three key takeaways going into Election Day.

Poliquin has helped and hurt himself by finding a record and refusing to discuss the presidential race, but key attacks in the race haven’t changed much since 2014.

Poliquin, a former state treasurer, benefited from not having a voting record in 2014, when he hit Cain selectively for voting to raise taxes during her decade in the Maine Legislature. Now, he has a record, and it has cut both ways for him.

On one hand, Poliquin can point to bipartisan actions, such as working with the rest of Maine’s delegation to head off an attempt to strip budget language that could boost domestic shoemakers including New Balance, which employs 900 in Maine and opposing the Trans-Pacific Partnership.

On the other, he has stuck to his party’s line on most pocketbook issues. For example, Cain has hit him for supporting a Republican budget in 2015 that would turn Medicare into a voucher program for new enrollees.

Poliquin also has refused to say whether or not he backs Trump, which has provided more fodder for Cain, a longtime Clinton supporter. He has blamed the media for trying to drag him into a “circus,” but Cain has said it’s “not too much to ask” him to voice an opinion.

But that’s basically what’s new in the campaign.

As they did in 2014, Poliquin and his Republican allies have savaged Cain’s support of a carbon tax in debates and TV ads saying they will kill jobs, even though her statement of support in that year’s Democratic primary was vague and in the context of a revenue-neutral tax. In an interview on Thursday, she called those ads “fearmongering.”

In their ads, Democrats have focused on Poliquin’s “Wall Street” history as a New York City investment manager, focusing on a controversy from 2012 relating to his 12-acre coastal estate in Georgetown, where his enrollment in a tax break program intended for commercial forests allowed him to pay $21 in taxes in one year on 10 acres of the property, despite a deed restriction largely barring tree harvesting.

Those attacks have been further amplified with astounding levels of outside spending in a crucial district for the national parties.

We know that you’ve heard these lines because Maine’s 2nd District has seen more TV ads than any other U.S. House district, according to the Wesleyan Media Project, which counted 9,327 commercials in Maine between mid-September and mid-October — a daily average of 333.

Why? Part of it is because the candidates have raised $6.3 million between them this time, compared with $3.7 million in 2014.

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But the bigger reason is outside spending, which has exploded from $3 million two years ago compared to $10.4 million as of Friday, with Cain benefiting from more than $6 million of it.

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The 2nd District is more rural and conservative than the rest of Maine, but it still leans Democratic, and the party held the seat for 20 years before Poliquin won it. That’s why Democrats want it back.

But even if they get it, they’re not primed for a majority: The 2nd District is one of the University of Virginia Center of Politics’ 15 Republican-held toss-up seats, but it projects that while Democrats may gain between 10 and 15 seats this election cycle, it’s still short of the 30 they need to lead.

Scant polling indicates a close race between Cain and Poliquin, but the toss-up presidential race is an X-factor.

In presidential seasons, we often look down the ballot to see who may get a bump. In 2012, Democrats took back majorities in both houses of the Maine Legislature as Mainers backed President Barack Obama’s re-election.

But in Maine’s 2nd District, we just don’t know how that will go. Clinton has proven to be far less popular than Obama with the state’s Democrats and younger voters.

Late last month, Trump capped his courtship for one of Maine’s four Electoral College votes in Maine’s 2nd District with his fifth visit to the state, a rally in the gymnasium of a Christian school in Lisbon.

A poll released Saturday by the progressive Maine People’s Resource Center showed a tie, with Trump with 42.6 percent to Clinton’s 41.1 percent in a four-way race, with Libertarian Gary Johnson and Green Jill Stein combining for 10 percent with another 6 percent undecided. On Friday, FiveThirtyEight had Trump’s chances of winning the district at 54.5 percent.

There has been scant polling in the Poliquin-Cain race. A September poll from Colby College had him 5 points up and a recent poll from the Portland Press Herald had Cain slightly up, but within the margin of error with a sample that Poliquin’s team denounced as oversampling higher-educated voters.

Get-out-the-vote efforts ramped up this weekend. Maine Democratic Party spokeswoman Katie Baker said the party planned to send out more than 1,500 volunteers working in the district. Her Republican counterpart Nina McLaughlin declined to give a figure but said their volunteers would be “working hard to get out the vote” statewide.

Poliquin spokesman Michael Byerly said the campaign has “more than 100 people currently deployed, and we expect to have several hundred over the weekend.” They’ll be aided by a team from House Majority Whip Steve Scalise, R-Louisiana, who also helped Poliquin in 2014, according to POLITICO.

But Cain said even if Clinton can’t carry the district, she can win, adding that she’s approaching Tuesday “with a clear head and knowing that we left it all on the field.”

She told a reporter something similar in 2014. We’ll see if it works.

Michael Shepherd joined the Bangor Daily News in 2015 after three years as a reporter at the Kennebec Journal. A Hallowell native who now lives in Augusta, he graduated from the University of Maine in...