LUBEC, Maine — It was quiet when the tiny plane carrying Senator Susan Collins, Republican of Maine, landed in Eastport just before noon on the Fourth of July. No blueberry-pie-eating contest, no parade and no Navy ship waiting in the harbor, its traditional place taken by a hulking cruise liner, docked amid the pandemic and yet to set sail.
Unlike previous years, Ms. Collins was not staying anyway; she was there to board a motorboat to visit Lubec, one of the easternmost towns in the contiguous United States with a population of about 1,300, for a small but hearty parade where enthusiastic waves and awkward elbow bumps took the place of handshakes.
Such were the lengths to which the senior senator from Maine was forced to go on Independence Day to connect in person with voters as she stares down the toughest re-election race of her career — and one that could determine whether Republicans retain control of the Senate in November. The nonpartisan Cook Political Report has rated the race a tossup, and with President Trump’s decline in national polls dragging down Senate Republicans around the country, Ms. Collins, 67, is facing ample headwinds.
She is toiling to find a way to defy those trends — she refused to say whether she would vote for Mr. Trump in November, and said she would not attack the presumptive Democratic presidential nominee, Joseph R. Biden, Jr. — but is well aware that doing so in a polarized political environment will be challenging.
The pandemic has upended her standard campaign playbook and raised the stakes of every interaction Ms. Collins has in Maine. So on Saturday, a whirlwind of plane and boat rides offered a crucial opportunity for her to look voters in the eye amid a contest that is being fought primarily through political ads flooding the state’s airwaves.
“I would be all over the state every single minute that I wasn’t in Washington,” Ms. Collins said in an interview, calling the current environment “surreal.” Instead, her campaign schedule has been limited to virtual meetings and fund-raisers and the few remaining outdoor events that have survived the coronavirus restrictions.
“That’s what’s frustrating to me in this pandemic, because I can do this in a rural area, at an outside event, but the vast majority of fairs and festivals in our state have been canceled,” Ms. Collins said. “I think that’s a huge loss for me because people know that I’m there because I want to be there, and it energizes them.”
After a quick lunch on the boat back to Eastport, it was back to the plane, where Ms. Collins put on a fresh cloth mask, emblazoned with a patriotic horse, and endured a bumpy flight across the state in time for another parade, this time in the woodlands of Jackman, a town of just over 800 people.
After coasting to a fourth term in 2014 with 69 percent of the vote, Ms. Collins is now among the Senate’s most endangered incumbents. She is being handily out-raised by Sara Gideon, the speaker of the Maine House and her likely Democratic opponent, and outside political groups seeking to oust the sole remaining New England Republican in Congress, one of a nearly extinct breed of moderates who once comprised a powerful centrist bloc.
The Maine Legislature, after reaching a bipartisan agreement to adjourn in March, remains out of session, freeing Ms. Gideon to appear at a string of virtual events and make individual appearances at local hospitals and other facilities. Ms. Collins spends most weekdays in Washington working on Senate business, leaving her few opportunities for face-to-face campaigning before Election Day.
“It’s a more challenging environment in which to reach people,” Ms. Collins conceded on Saturday as she crisscrossed the state. “Being grossly outspent makes it harder, because I can’t offset that by increasing the number of appearances that I’m doing.”
While she has split with Mr. Trump more than any other Republican senator in the 116th Congress, Ms. Collins’s carefully cultivated reputation as a moderate has been damaged during his tenure, particularly after she backed the $1.5 trillion tax-cut package in 2017 and cast a decisive vote to confirm Justice Brett M. Kavanaugh to the Supreme Court in 2018. When Justice Kavanaugh sided with the court’s conservative majority in an abortion decision last week, progressives renewed their attacks.
Unlike in 2016, when she very publicly declared that she would not vote for Mr. Trump, Ms. Collins refused on Saturday to say how she planned to vote come November.
“My inclination is just to stay out of the presidential and focus on my own race,” she said.
As for Mr. Biden, “I do not campaign against my colleagues in the Senate,” she added, explaining that taking on Mr. Biden, whom she knows “very well” from their days serving together there, would be akin to violating her own rule.
Yet national Democrats are not holding back against Ms. Collins. They are spending huge sums on an onslaught of television, radio and YouTube ads that frame her as beholden to corporate donors and drug companies and unwilling to counter Mr. Trump and Senator Mitch McConnell of Kentucky, the majority leader. As of June 9, outside groups have spent $11.9 million on TV and radio ads against Ms. Collins, compared to $6.7 million in her favor, according to the Collins campaign.
Earlier this month, Ms. Gideon, who is widely favored to win the Democratic primary on July 14, announced that she had raised $9 million in the second fund-raising quarter of the year, three times what Ms. Collins announced in a preliminary report ahead of the primary. Ms. Gideon, who also reported having $500,000 more cash on hand than Ms. Collins, is expecting another windfall after the primary: at least $3.5 million in funds raised during and after the confirmation of Justice Kavanaugh and tied to her helping confirm him, which Ms. Collins condemned as an attempted bribe aiming to sway her critical vote.
The quarantine restrictions imposed during the pandemic — including the cancellation of cherished annual events paying homage to a cornucopia of edible Maine bounties — mean that more families are likely to be at home, consuming the negative advertisements against her. (The Senate Republican campaign arm has also launched a flurry of ads to bolster Ms. Collins, attacking Ms. Gideon as an ineffective politician.)
All of which has Ms. Collins concerned.
“I am,” she said as she finished a jumbo lobster roll with a sprinkle of lemon — no mayonnaise or butter — on the boat ride back to Eastport. “But in the end, I think people in the state know me really well.”
Her fingerprints were all over the two towns — Lubec, overlooking a sparkling bay into Canada, and Jackman, tucked next to Moose River in the state’s northern timber country — where she has leveraged her seniority on the powerful Appropriations Committee to help guide funding to critical infrastructure projects.
In Lubec, where families watched the parade from inside their cars or from a distance on their porches, residents grabbed “Fishermen for Collins” bumper stickers and shouted their appreciation to her for the aid to begin building a safe harbor at the edge of the town, near the memorial dedicated to fishermen, some of whom had drowned in foul weather trying to reach shore.
And in Jackman, where Ms. Collins helped secure funding to lengthen the local runway so medical helicopters could safely land, the crowds of locals and weekend tourists — few wearing masks in a county that has seen just over two dozen coronavirus cases — marveled that the senator had made a point of coming to their parade.
“For her to come to a small town like Jackman, Maine — it means so much,” said Terry LaPlante, 57, who wore a “Black Flies Matter” shirt to the parade in Jackman. “It’s the working people — it’s the people who work their asses off for a living.”
“We’re real Mainers — this is real Maine,” declared Angie Lyon, standing next to Mr. LaPlante while Ms. Collins prepared to honor the 200th anniversary of the settlement of the nearby river.
The tiny logging hub of Jackman — where a clown on an A.T.V. tossed candy at children sitting on the curb and tractor-trailers with fluttering Trump flags honked to woops and cheers — skews heavily Republican.
And while the car trailing Ms. Collins (like previous years, she preferred to jog and wave from a distance) did not flaunt any pro-Trump signs, voters said the “R” next to her name was likely enough for them.
“I wish someone would come out of the woodwork and challenge her as a conservative, but I will support her,” said Marco Carrier, 56, who works in the wood industry. “She keeps me on edge, but the important calls, she’s done right.”
But, referring to the liberal city in Southern Maine that is significantly larger than most cities and towns in the state, he added, “Portland makes the call.”
The challenge for Ms. Collins extends further afield, however.
In Lubec, Sam Winch, 65, a retired journalism professor, planted a sign blaring “It’s time to retire, Susan” next to his Biden campaign sign as he stood outside his home, peanut butter and jelly sandwich in hand, to watch Ms. Collins briskly walk by and exchange a cordial hello.
“I have a soft spot for Susan Collins in my heart,” Mr. Winch said, noting that she had been a moderate and “more thoughtful than your average partisan senator” during her years in Congress. “But, unfortunately, the best I can do to help bring the Senate to being more functional is to retire her.”