AMNA NAWAZ: Despite Democratic concerns about Biden's candidacy, new polling out today shows the state of the race has not drastically changed since the debate.

To walk us through these new numbers, I'm joined now by NPR's Domenico Montanaro.

Always good to see you.

DOMENICO MONTANARO, Political Editor, NPR: Good to see you too.

AMNA NAWAZ: So as more lawmakers are coming out calling for him to step aside, the question has been how voters look at this.

The latest numbers from PBS/NPR/Marist polls actually show that Mr. Biden is now leading former President Trump 50 to 48 in a head-to-head matchup.

When third parties, however, are factored in, he slips slightly, but it's still a statistical dead heat there, with Trump at 43 percent, Biden at 42.

What stands out to you about those numbers?

DOMENICO MONTANARO: Well, I mean, it's been a marginal race the entire time.

Not much clearly has changed nationally when it comes to Trump versus Biden.

I also think we still have to take into consideration that there's humongous antipathy toward Donald Trump.

I mean, you easily could see in all these numbers that more than half the country doesn't want Donald Trump to be president again, but it's really less Joe Biden versus Donald Trump somewhat and Joe Biden versus the couch.

AMNA NAWAZ: So, should we take these numbers to mean that voters don't actually have the same concerns about Biden's age or his mental acuity as Democratic lawmakers who are asking him to step down to?

DOMENICO MONTANARO: Not necessarily.

And the other question is, what are their choices, right?

But when we look at some of the numbers inside the survey, actually, two-thirds of respondents said that Biden does not have the mental fitness to be president, but character may matter more; 68 percent said that it's more concerning to have a president who doesn't tell the truth than one who might be too old to do the job.

So, pretty remarkable numbers.

And I think that really says something about these two candidates and what people think is important.

Yes, we saw, like we just showed, two-thirds of people saying that Biden lacks the mental acuity.

However, at the same time, if you think somebody isn't telling the truth, doesn't have the character to serve, and that's what we're seeing, that Biden has more points for character and honesty than Donald Trump.

AMNA NAWAZ: OK, so some of Mr. Biden's critics also argue that another younger Democratic candidate might inspire more enthusiasm or could more easily beat Donald Trump.

Is that showing up in the polling?

DOMENICO MONTANARO: Well, look, I mean, we tested four people, President Trump, Vice President Harris, Michigan Governor Gretchen Whitmer and California Governor Gavin Newsom.

Everybody did about exactly the same.

Now, maybe that's because they're a generic Democrat and they sort of test that way.

There are slight nuance differences between each of the candidates.

Newsom does a little bit better with independents.

Partially, that could be because he does appear on FOX News quite a bit and there's more exposure to some of those Republican-leaning independents.

Vice President Harris does much better than President Biden, by the way, with nonwhite voters and younger voters.

Gen Z millennials, she does 12 points better than Biden and, with nonwhite voters, 10 points better.

So, something to consider there, especially when you think about who has electoral prowess or not.

Now, when these candidates start to actually run, if they were to run, if they were to replace President Biden, then they get to make the case for themselves, or they also get a lot more media scrutiny too.

AMNA NAWAZ: OK, so let's add some context here, because viewers will have seen Amy Walter of The Cook Political Report here just a couple of days ago walking us through some of their polling at the state level.

And what she showed us was that we saw voters in six states, six states that were previously tossups or likely Democratic states move closer to Trump after the debate.

Those include the battleground states of Arizona, Georgia, and Nevada.

How do you square that at the state level with what we're seeing in these polls at the national?

DOMENICO MONTANARO: Well, not that surprising, to be honest, because national polls reflect what the country feels at large.

But we are not in a situation where you have the popular vote determining who the president is.

And because Democratic votes are so concentrated on the coast, one in five Democratic votes come from California and New York.

That's it.

So if you have that kind of concentration and you don't have the Democratic votes spread out into some of those swing areas, then those swing areas, those swing states are slightly more conservative.

So, frankly, President Biden has had this sort of lead with Trump or within the margin.

A two-point lead for a Democrat nationally is not really that good for somebody like Biden, because it needs to be probably a little bit bigger than that to translate to electoral vote success.

AMNA NAWAZ: OK, I do want to get your take on what President Biden had to say about the polls himself last night.

Take a listen.

JOE BIDEN: How accurate does anybody think the polls are these days?

I can give you a series of polls where you have likely voters, me versus Trump, where I win all the time.

When the unlikely voters vote, he wins sometimes.

The bottom line is, all the polling data right now, which I think is premature, because the campaign really hasn't even started.

DOMENICO MONTANARO: Well, the campaign's been going on for two years.

He's actually right that those who say that they're definitely voting are doing better for Biden.

But I will say, politicians always say that the polls are wrong when they're not good for them.

AMNA NAWAZ: That's NPR senior political editor and correspondent Domenico Montanaro.

Always great to see you.

Thank you.

DOMENICO MONTANARO: You too.

Thank you.