GEOFF BENNETT: One of the Senate races drawing the most attention is unfolding in Maine, where five-time Republican Susan Collins faces a tough challenge from Democrat Troy Jackson, a former logger and state legislator.

The race is rated a toss-up, with both parties fighting for a seat that could determine control of the U.S.

Senate.

Our Lisa Desjardins reports now from Maine.

LISA DESJARDINS: In the exact center of Maine, for the small town of Brownville, a big moment.

MAN: I'd like to thank you for everything that you have done for our organization.

SEN.

SUSAN COLLINS (R-ME): Thank you.

Thank you too.

(APPLAUSE) LISA DESJARDINS: Thanking Republican Senator Susan Collins for helping bring $2.8 million here, including money to replace this aging fire station.

SEN.

SUSAN COLLINS: Helping our first responders has been a top priority for me.

LISA DESJARDINS: This is not a campaign event, but it is central to Collins' argument.

SEN.

SUSAN COLLINS: Good to see you.

LISA DESJARDINS: She has brought some $1.5 billion to her state, funding 45 fire stations, along with water treatment sites, health centers, you name it.

SHELLY EKHOLM, Maine Voter: Senator Collins is down-to-earth hardworking woman for the state of Maine and for our country.

She fights for everyone, not just a particular party.

LISA DESJARDINS: A hundred and thirty miles and a political light year southwest, a different theory of what Maine needs.

TROY JACKSON (D), Maine Senatorial Candidate: You don't get to vote to fund Donald Trump's agenda and then come home and tell us how concerned you are about it.

LISA DESJARDINS: Troy Jackson is the Democratic candidate for Senate running as a progressive.

He's a logger turned politician who served as state Senate president.

But the message here was less about him and more about opposition to President Trump and Collins.

KARSTEN REES, Maine Voter: I think we're ready for a change and somebody who votes more consistently with Maine interests.

LISA DESJARDINS: Further south in Kennebunk, even with no candidates in sight, the election is in the air, and some are struggling, like Bill Amabile.

BILL AMABILE, Maine Voter: It's really a tough decision for me.

I have supported her in the past.

LISA DESJARDINS: Could go either way at this point for you?

BILL AMABILE: Yes, yes.

I'm still not completely decided on it.

LISA DESJARDINS: Maine likes to buck political rules.

In 2020, this was the only state to split its top races, voting for Joe Biden for president and Susan Collins for Senate.

So while Collins will need Republican faithful, she also will need loyalty from some of the most independent-minded voters in the country.

NICK PAPIN, Troy Jackson Supporter: In 2020, I voted for Biden and I voted for Susan Collins to be senator.

LISA DESJARDINS: Susan Collins now, where are you on her?

NICK PAPIN: I won't support her ever again.

LISA DESJARDINS: Nick Papin runs a small business and lives with his partner in Kittery, Maine.

He was never politically active until last fall.

GRAHAM PLATNER (D), Former Maine Senatorial Candidate: Health care is a human right.

LISA DESJARDINS: When he heard Democrat Graham Platner and his message against big money in campaigns.

But a series of scandals rose around Platner, including a rape allegation, which he firmly denied, that led him to drop out.

After that, Jackson was picked, not by voters at large, but by delegates at a convention.

He wasn't your first choice.

NICK PAPIN: Correct.

LISA DESJARDINS: Where are you now?

NICK PAPIN: Now I'm fully behind Troy.

LISA DESJARDINS: In part because he is furious at Collins.

He says she hasn't stood up to President Trump enough.

NICK PAPIN: Having split my vote for my whole life, the Republican Party has gone rogue.

It's a race to the bottom.

Who can be Trumpier than Trump?

Their values have drifted so far away from my core values that I don't see the opportunity to vote for another Republican in my lifetime.

LISA DESJARDINS: But as some in this rocky, hardy state see Collins as part of a storm, others see her as what's protecting Maine.

LINDA POST, Susan Collins Supporter: If we have someone besides her there, that Maine will get -- will get nothing.

They're not going to care about Maine.

We're such a small state.

LISA DESJARDINS: Linda Post lives in Owls Head in Maine's Midcoast.

Her support of Collins is personal.

LINDA POST: This was him at the St.

George Legion.

LISA DESJARDINS: Linda's dad, a World War II veteran, depended on the heating assistance fund LIHEAP, but a glitch cut it off and threatened his heat.

For weeks, Linda ran into red tape.

LINDA POST: His income was Social Security.

That's all he had, so I reached out to Senator Collins' office.

LISA DESJARDINS: She says her dad's heating oil assistance was quickly restored, just one example of why she believes Maine needs Collins.

LINDA POST: It's important, I think, that we have someone that has her experience, her background.

She knows her way around Washington.

And I don't think it's time to change.

LISA DESJARDINS: The skyrocketing cost of heating oil has become a larger campaign issue.

TROY JACKSON: Today, with the war in Iran, heating oil is at $6 a gallon.

LISA DESJARDINS: One in the onslaught of ads.

More than $200 million has been spent by the campaigns and outside groups, the largest per voting population of any state.

NARRATOR: Troy Jackson is a creep.

MAN: She increased her wealth over $10 million.

LISA DESJARDINS: Part of a campaign cycle that has been ruling for voters and candidates.

SEN.

SUSAN COLLINS: More than a billion dollars.

LISA DESJARDINS: They debated four times this month with substantive disagreements, but also headlines when a protester interrupted and this exchange happened.

SEN.

SUSAN COLLINS: This is obviously one of Troy's supporters.

TROY JACKSON: Oh, shut up.

I didn't -- I don't even know that kid.

LISA DESJARDINS: Jackson later defended telling Collins to -- quote -- "shut up."

Throughout the campaign, there have also been questions about this replacement candidate's readiness and how he will make good on pledges like Medicare for all or changing campaign finance laws.

It's easy to say that we want to change money in politics.

But tell me, exactly how do you plan on doing that?

TROY JACKSON: Yes, and there's no doubt that it's going to be tough with President Trump in there, but obviously in two years there will be a new president, and a simple majority might be able to do that, getting rid of the filibuster, so that we don't end up doing -- having 60 again.

LISA DESJARDINS: You would do that?

TROY JACKSON: I -- absolutely.

Listen, I have fought for majorities here in Maine.

I have been in the minority.

You don't build majorities so you can let a handful of people block you.

QUESTION: Discuss these controversies.

LISA DESJARDINS: For Collins, there were questions about a ProPublica report, alleging the FBI wanted to investigate her and others for potential corruption centered around a convicted former defense contractor.

SEN.

SUSAN COLLINS: These allegations are completely false, and they are very offensive.

LISA DESJARDINS: But her record was center stage.

She raised her no vote on Secretary Pete Hegseth as a sharp break from Trump and defended her 2018 vote for Supreme Court Justice Brett Kavanaugh as based on qualifications and in line with votes for liberal justices.

She opposed President Trump's reelection and voted no on last year's Big Beautiful Bill.

But some voters we spoke with said she should be more aggressive in opposing Trump.

I asked her about this.

SEN.

SUSAN COLLINS: What I think some people want, which I don't think is effective, is for me to rant and rave.

The fact is the people of this country disagreed with me, and they elected Donald Trump to be president.

I think it's a mistake for any member of the Senate to so cut off relationships with a Cabinet of a president that they can't get anything done.

I have been able to get things done.

LISA DESJARDINS: On one side, those who believe in what Susan Collins has and can do for the state, and see in Troy Jackson a flawed politician without clear plans.

LINDA POST: It was a mistake to put him in place to run against Susan.

LISA DESJARDINS: Why?

LINDA POST: Because I think he's way out of his league.

LISA DESJARDINS: On the other, voters angry with President Trump, who sees Susan Collins as enabling him.

NICK PAPIN: I don't believe her anymore.

There's an expression we have, Susan Collins is always there when you don't need her.

I have never seen her take a stand against Don -- I mean a real stand against Donald Trump.

LISA DESJARDINS: Polls show this beautiful state is also closely divided.

Above it is a pressing decision, whom do they trust to steer the future?

For the "PBS News Hour," I'm Lisa Desjardins reporting from across Maine.