Christian LaMontagne has started slowing his lobster boat down.

The 27-year-old fisher spends longer on the water when out hauling traps in Casco Bay, but the trade-off helps him save fuel at a time when costs have surged. Before the US war with Iran began in late February, filling his tank cost about $350 a week. Now it’s doubled to nearly $700.

“Last year at this time I had to go out and catch 40 lobsters to fill up my tank, this year it’s over 104,” LaMontagne said at Widgery Wharf in Portland, where his 34ft Wayne Beal boat is docked just steps away from the hum of tourists in the city’s Old Port.

Practically every part of Maine’s billion-dollar lobster industry has been squeezed by Trump administration policies like the Iran war and sweeping tariffs. Despite the economic pressures shaping his vote, LaMontagne remains undecided in the state’s tight Senate race.

One of the most closely watched contests of this midterm cycle pits Troy Jackson, the progressive lumberjack who mounted a breakneck 101-day campaign, against Susan Collins, the entrenched Republican incumbent seeking a sixth term. Democrats see Maine as critical to their effort to retake the upper chamber, though recent polling shows the nominees neck-and-neck heading into 3 November.

The race was beset by turmoil early on after the former Democratic nominee, Graham Platner, withdrew after a series of controversies, culminating in a sexual assault and rape allegation that he denied.

Now with less than a week to go, pocketbook concerns increasingly blend into a broader judgment of Donald Trump’s second administration. And Maine’s conflicted voters may decide the election.

In the final stretch of this often-acrimonious Senate competition, Jackson has cast himself as the working-class alternative to Collins’s three decades in Washington, arguing that her reputation for independence masks a voting record that ultimately benefits Trump.

The federal funding that she has brought in is “a pittance compared to what we’re losing”, Jackson said at a recent campaign event for Maine veterans in Brunswick, adding that Collins “takes credit for an awful lot” but won’t take credit for helping pass Trump’s One Big Beautiful Bill Act, which he said is “crushing” the state.

Jackson has also worked to yoke Collins more closely to Trump after a ProPublica report in September that revealed the FBI had investigated the senator over an alleged pay-to-play scheme involving a campaign donor. The inquiry reportedly withered after Trump dismantled the justice department division handling the case.

He called the episode “corruption of the highest order”, while Collins’s office dismissed the report as “categorically false” and noted there were never any allegations of wrongdoing by the senator’s campaign.

“The reality is that 100% of the time, when Donald Trump needs her, Susan Collins is going to be there,” Jackson said during one of four televised debates this month, while also invoking the senator’s vote to confirm Brett Kavanaugh to the supreme court, which later helped overturn the constitutional right to abortion in 2022.

Collins, whom Trump once derided as “absolutely atrocious”, argues that her willingness to break with the president and her party sets her apart from most Republicans. “I decide my votes on what I believe is best for Maine and for America, not on whether or not any president, and I’ve worked with five, is for it or against it,” she said at a recent campaign stop.

On the trail, the senator points to her vote against repealing the Affordable Care Act, her vote to impeach Trump after the January 6 insurrection, her opposition to Pete Hegseth’s nomination as defense secretary and her support for a war powers resolution limiting military action against Iran without congressional approval. (The Collins campaign did not respond to the Guardian’s request for an interview.)

However, a New York Times analysis found that while Collins has broken with her party 17% of the time during the current Congress, roughly in line with her rate of defections during Trump’s first term, those breaks have rarely slowed the president’s agenda since his return to the White House last year.

One example was Trump’s signature domestic policy package that imposed steep Medicaid cuts, including billions affecting Maine. Although Collins opposed the bill’s final passage, she supported a key procedural vote that allowed it to reach the Senate floor.

Collins is also the only Republican senator up for re-election in a state Trump lost in 2024, leaving her exposed to the broader backlash against the administration. A recent Marist poll found that only 42% of likely Maine voters approve of Trump’s job performance, while 41% say their congressional vote is primarily a vote against him.

“Jackson, in some ways, seems almost irrelevant,” said Dan Shea, a professor of government at Colby College. “I think it’s about whether or not [voters] can tolerate giving Trump one more vote in the Senate.”

Meanwhile, Collins’s ability to secure concessions from the Trump administration may be her greatest boon on the campaign trail, and Jackson’s biggest disadvantage.

In recent weeks, she has touted a major Pentagon contract for the Bath Iron Works shipyard, the release of more than 300,000 barrels of heating oil to ease costs across New England and Trump tariff exemptions benefiting Maine industries caught in the US-Canada trade war.

As a freshman senator, Jackson would face a steeper climb in directing federal resources to the state, particularly if Democrats remain in the minority.

Faced with the reality of rising costs and an unpopular president, Collins’s former supporters are weighing their options. Beyond gas, heating oil has emerged as another flashpoint in Maine, where nearly half of households rely on it to make it through the winter. The average price of a gallon now exceeds $6, a record high, according to the state’s department of energy resources.

“I put in 131 gallons of oil. It wasn’t even filling the tank, and it was $729,” said Cheryl Clukey, 77, a retired school principal from Augusta. “I’ve never had that before, and I’m scared.”

Clukey, who has voted for Collins in the past and was raised Republican, said the senator’s 30 years in Congress are “enough”.

At Jackson’s campaign events in the final week before election day, enthusiasm is palpable. Yet many supporters appear motivated less by Jackson himself than by opposition to the president.

“I would have voted for anybody who could put brakes on Trump. If I’m honest, Troy [Jackson] would not have been my first pick,” said Susan Cellucci, 64, of Scarborough. “But I would’ve voted for pretty much anybody who is a Democrat because I think that this guy in the White House and his administration needs to be brought back to earth.”

In Biddeford that anger remains particularly acute, after a federal immigration agent shot and killed 26-year-old Joan Sebastián Durán Guerrero, a Colombian man and father, at a traffic stop in July.

“This is not something that happens here in a small seaside town,” said David Kurtz, a Biddeford city councilor and local attorney backing Jackson. “We’re seeing those chickens come home to roost for people … There are people who are never going to vote Republican again, no matter who that person is.”

Still “no result will surprise me,” Kurtz added, noting that Collins has repeatedly outrun the political odds in the past, including her nine-point 2020 victory over former Maine house speaker Sara Gideon despite trailing in most polls.

In 2020, Collins won re-election with the help of ticket-splitters who backed her for Senate while sending Joe Biden to the White House. One of them was Rick Dolliver, a registered Democrat and seafood restaurant owner in Ogunquit, who plans to support her again this year.

“She’s given Maine a once-in-a-lifetime opportunity to bring more federal resources to our state,” he said. “She’s proved that she’s the only member of the delegation who can effectively push back against [Trump’s] bad policies.”

Dolliver pointed to Collins’s role in creating the Paycheck Protection Program during the Covid pandemic, which he says helped keep employees on payroll while his restaurant was shuttered. He described Jackson as a “rookie” with “no chance of getting anything done” if elected.

For undecided voters like LaMontagne, the question is whether Jackson, a former state senate president, can match the influence that comes with Collins’s seniority and longstanding relationships on Capitol Hill.

“Do I agree with her on a lot of stuff? Probably not. Do I agree with her on some stuff? Yeah, maybe. Is she an ally of the lobster fishery right now? Absolutely,” LaMontagne said, pointing to funding Collins has secured and regulations she has helped ease for his industry.

Yet he is also hungry for change.

“The status quo sucks,” he said. “Frankly, it just kind of sucks when your business makes less money every year and there’s no change in sight.”

While Collins benefited from the turmoil that engulfed Democrats after Platner’s implosion, she may now be more vulnerable than at any point in the campaign, as some independent voters who have backed her in the past weigh Jackson as their clearest option for checking Trump.

Democrats also appear more energized this cycle. Many in the party will likely “crawl over broken glass to get to the polls”, whereas Republicans are “sort of hanging their head as they drive by the gas station and turning off the news”, Shea said. Jackson could also benefit from strength in the state’s gubernatorial race. Hannah Pingree, a former state representative, is leading Republican Bobby Charles by double digits in several polls.

That includes voters like LaMontagne, who said he was “excited” to vote for Pingree.

As he considers his options ahead of Tuesday, however, LaMontagne said backing Jackson would still require something many Mainers are wrestling with: a leap of faith.

“Taking some trust that he has pivoted the campaign enough to have a good vision for the country, and that the people around him will help lift him up to do a good job,” LaMontagne said.

“But the question is, is it better than Collins?”

For Jackson, the answer is straightforward.

“I give a shit about people’s families,” he said. “If you think that you want to vote for somebody that backs the billionaires, well, God bless you. That isn’t me.”