GEOFF BENNETT: Both candidates are using the final hours of campaigning to make their messages clear in key battlegrounds, which we will be keeping a close eye on tomorrow.

AMNA NAWAZ: Our Lisa Desjardins is at the PBS News super screen for a look at the various paths to victory for both candidates.

Lisa, good to see you.

LISA DESJARDINS: Good to see you.

AMNA NAWAZ: All right, let's talk about Pennsylvania.

We have heard about Pennsylvania, Pennsylvania, Pennsylvania.

Why is it so critical for both candidates on their path to 270?

LISA DESJARDINS: The Keystone State living up to its name.

Let's look at how The Cook Political Report rates these races, as you know, seven key swing states.

And if you look at what both campaigns see as a potential likelihood in the way states are leaning right now, then you have North Carolina, Georgia going for Trump, Arizona going for Trump.

And let's even say Nevada, which right now is about even goes for Trump.

In this situation, if Kamala Harris is able to win Wisconsin and Michigan, the so-called blue wall, her only way of getting to the presidency is through Pennsylvania.

Now, even if she was able to win here in Nevada, if she loses Pennsylvania, Trump still wins.

Same thing.

Even Arizona, if she's able to win there, she still needs to win in Pennsylvania.

So, for the Democrats, the Keystone State is absolutely critical.

GEOFF BENNETT: So if Pennsylvania is a must win for Harris, what are the must-wins for Trump?

LISA DESJARDINS: Right.

Let's look at the alternate scenario here.

So let's say that Trump is able to win in Arizona and in Nevada.

Now, here we go.

Let's leave Pennsylvania off the board for just a second and leave it blank.

Now, he -- if he can't win in North Carolina and Georgia, his path gets much more difficult.

I will show you what I mean, 16 points here in North Carolina.

Let's say it goes to Kamala Harris.

That puts her at 267, just three points away from winning at all.

So, in other words, if Trump wants to win, he's got to win in Pennsylvania and in Georgia.

And that's a strange combination.

If he's able to do well enough in Pennsylvania and still lose North Carolina, that's a scenario Republicans don't really see happening because of the way voter groups overlap.

In other words, some of these early states in the night, North Carolina and Georgia, the South, the Southern wall, Republicans really want that to come in for them.

If Trump can't win in both of these states, he really may have a problem for the rest of the night.

AMNA NAWAZ: So, Lisa, move us away from the battlegrounds for a second, because Iowa and New Hampshire are back in the headlines, some surprising polling over the weekend and some shifts.

What happens if those states are in play?

LISA DESJARDINS: That's right.

Two different sets of expectations and effects from these states.

Now, let's talk first about Iowa.

Again, let's start with this base scenario where Harris is able to win the blue wall and that second district in Nebraska, Trump wins these other states in the Sun Belt.

Let's say Harris is able to switch Iowa and its six electoral votes.

That gets her up to 276, but it really doesn't change the map for her.

She can still win here, lose here.

It really doesn't affect her win or loss ability as much as it would give her more points on the board.

New Hampshire is a different situation, because this is the situation Republicans fear is Harris running the blue wall through these three states, getting 270 electoral votes.

They need another path.

This is why you saw vice presidential candidate J.D.

Vance go to New Hampshire, try to pick up these four electoral votes, gets them to 272.

They just want another potential pathway to the presidency.

Now, is this likely?

Both parties say maybe not, but Republicans think they have a real chance in New Hampshire, where they don't have early voting, and voting will be starting tomorrow.

GEOFF BENNETT: Well, let's shift our focus back to the battlegrounds, Lisa.

How are things shaping up there for the campaign?

LISA DESJARDINS: OK, so where the heck are these battlegrounds?

Folks, it is unbelievably close.

Let's take a look at these races.

Arizona, Trump plus-two, Georgia plus-one.

Look at this, Michigan, Harris plus-one, Trump plus-one.

Even in North Carolina, even in Pennsylvania, Wisconsin plus-one.

I don't know if I have ever seen a Group of Seven battleground states this close.

Now, of course, this isn't a statement of the exact state of the race, but it tells you that it's close.

It's a virtual tie, all of these races within the margin of error, most certainly as we stand and look at it right now.

AMNA NAWAZ: Lisa, meanwhile, some new polling from PBS News as well.

What stands out to you?

LISA DESJARDINS: Right, some big numbers.

As we heard earlier, look at this.

Right now, in national likely voters, we see Trump down by four points over Harris, and that is Harris outside the margin of error.

So that's a trend that the Democrats would certainly like to see.

And something else Democrats like to see, the gender gap in terms of men has certainly changed just since October.

Look at this, it was a 16-point gap Harris had with men.

Now look at that, just four points.

That's an incredible 12-point difference.

But I will also say Trump and Vance have also made up ground with women.

They have started to close that gap on their end.

GEOFF BENNETT: Lisa Desjardins, our thanks to you, as always.

LISA DESJARDINS: You're welcome.