GEOFF BENNETT: Republicans and Democrats in Nevada, North Dakota and South Carolina select their party nominees today, but much of the nation's political focus will be on Maine, where the end of the Senate primary marks the beginning of one of the most consequential general election races in the country.

Whichever Democrat emerges will take on five-term incumbent and Republican Senator Susan Collins.

That's expected to be Graham Platner, even as he grapples with one scandal after another.

TODD RICHARDS, Platner Supporter: I'm still going to vote for Graham because if his wife, Amy, can get over it and still stay married to him, then I think, as a voter, I should be able to get over it and still vote for him.

BARBARA FENLASON, Collins Supporter: She doesn't always vote the way I like, but I call her the lesser of two evils.

I hate to say it, but the other side is -- there's a lot of negative things coming out that I wouldn't want in a dogcatcher in my town.

GEOFF BENNETT: Alex Seitz-Wald is deputy editor of the Midcoast Village and a former senior national political reporter for NBC News.

Alex, it's great to see you.

ALEX SEITZ-WALD, Deputy Editor, Midcoast Villager: Thanks for having me.

GEOFF BENNETT: So, as you well know, the Democratic Senate candidate, Graham Platner, he built this early lead leaning into this story of him as an oyster farmer, his personal story as a combat veteran.

He ran this insurgent outsider campaign, but his candidacy has been dogged by controversy, from scrutiny over this tattoo that he has that was linked to Nazi imagery, to allegations from former girlfriends about his behavior.

More recently, a former campaign staffer publicly argued he's unfit for office.

How are Democratic voters in Maine weighing those concerns against what many see as a potential, underscore the word potential, opportunity to flip a Senate seat?

ALEX SEITZ-WALD: Well, this latest round of controversies involving his relationships with ex-girlfriends and also sexting other women early in his marriage have definitely hit a little bit differently.

These are, of course, not the first scandals that Platner has dealt with, but while supporters brush past the ones in the fall about his old Reddit posts and his tattoo, kind of viewed it as bona fides, that he's a real working person with a checkered past, this latest allegation has divided Democrats.

There are some, largely women, who find it very disappointing, concerning, heartbroken, as one voter put it.

And then there's also people, more die-hard supporters, who view it as kind of part of an establishment attack on an outsider candidate.

But what I have not heard is any Democrats or people who had previously been supporting Platner who now say they're going to switch over to Susan Collins.

Instead, what I'm hearing a lot of is, like we heard from one voter, who said she's sickened that she has to vote for Graham Platner, but she will in November because Maine Democrats have been trying to oust Susan Collins for years.

They have run more conventional candidates in the past and lost.

She's a powerhouse who should not be underestimated.

And I think they're more willing to kind of take a risk and try something, anything different to get rid of her, given the stakes for the Supreme Court and everything else.

And whatever happens, we can't say that Maine voters didn't know.

There was just a new poll out that showed 90 percent of both primary and general election voters are aware of these allegations.

It's a state with very high voter turnout.

People are engaged.

So they are making a conscious decision about Graham Platner.

GEOFF BENNETT: And there are Democrats who believe that Senator Collins is more vulnerable in this cycle than she's ever been previously.

What, if anything, will tonight's results tell you about whether that assumption is actually true?

ALEX SEITZ-WALD: Yes, I mean, that's the big question because Democrats feel a bit like Lucy with the football with Susan Collins.

And there's this perception of a sort of silent Susan majority out there.

But in the primary results, I'm going to be looking at Platner's margin.

And at this point, if you're voting for anybody other than Platner in the primary, you're really doing it to send a message, as a protest.

So whatever percentage of votes are not for Platner, because there's no other real candidate in the race, those are voters that Platner is going to have to go after and bring back into the fold.

And I'm also watching the results in the other elections for governor, for Congress, which will tell us a bit about the mood of the electorate overall in Maine, regardless of the Platner specifics.

GEOFF BENNETT: And, in Washington, there are prominent Democrats who are supporting Platner, and they say that voters care more about economic issues than they do about anyone man's personal conduct.

Interestingly, that's an argument that many Republicans had made about Donald Trump.

I mean, what does that say about where the Democratic Party is right now?

ALEX SEITZ-WALD: Yes, I actually had a Platner supporter tell me that going through this whole experience has made him understand Trump voters for the first time, because a lot of Platner voters feel like they're being misunderstood, misrepresented by the national press.

And I think we're also just looking at a more transactional electorate.

They care about the policies, the vote.

They're getting more about the letter next to the person's name than the name of the person itself, because Collins is exactly the type of political figure that Maine has elected for years, temperamentally moderate, bipartisan, civil.

This has been the mold for decades.

Platner obviously completely breaks that mold, a very different style of politician, but it's a very anti-incumbent mood out there.

People are upset, and they might be willing to take a big chance on this unknown outsider.

GEOFF BENNETT: Final question, Alex.

Maine has a distinctive political culture that doesn't fit nicely into national narratives.

Once the results come in, what are the pundits likely to get wrong?

ALEX SEITZ-WALD: I think the biggest thing is the assumption that Susan Collins is easily beatable.

It's a blue state.

People assume that because we haven't voted for a Republican president since 1988, it should be easy.

But that's just not the case.

Collins has won again and again.

In 2020, when Joe Biden won Maine, Collins won by 9 percentage points against a uncontroversial, well-qualified Democrat who spent twice as much money as her.

GEOFF BENNETT: Alex Seitz-Wald, deputy editor of the Midcoast Villager, good to see you, friend.

Thanks for making time for us.

We appreciate it.

ALEX SEITZ-WALD: Thanks, Geoff.