AMNA NAWAZ: Latino Americans make up nearly 20 percent of the U.S. population, and this year are expected to be a critical constituency for both Republicans and Democrats in swing states.

And yet, as Judy Woodruff reports, the very idea of Latinos voting as a bloc betrays the diversity of history, culture, and perspectives within that community, which may also help strengthen it against the polarization we see in the country more broadly.

This report is part of her ongoing series, America at a Crossroads.

JUDY WOODRUFF: This is your parents, your mom.

SYLVIA GONZALEZ ANDERSH, Latino Voter: My mom, my dad.

JUDY WOODRUFF: Sylvia Gonzalez Andersh is a 67-year-old United States Air Force veteran.

SYLVIA GONZALEZ ANDERSH: Well, we were considered Mexican Americans.

That's what everybody called us.

RAFAEL POLO, Latino Voter: I am getting promoted to lieutenant commander.

JUDY WOODRUFF: Raf Polo is a 73-year-old United States Navy veteran.

RAFAEL POLO: At home, we spoke Spanish.

We drank the Cuban cafecito.

Have you ever had that?

(LAUGHTER) RAFAEL POLO: You go -- when we left the house, from the moment we stepped out, we were Americans.

JUDY WOODRUFF: They both live in Tucson, Arizona.

They consider themselves Latino, and they are both politically active.

But when it comes to the issues, like undocumented immigration, they simply don't see eye to eye.

How do you view the people who are trying to come into this country without documentation?

SYLVIA GONZALEZ ANDERSH: They must be pretty desperate to walk thousands of miles to get here and to go through all that agony.

But, as far as being on the border, I have been down there.

I mean, we're 100 miles from Nogales, from the border.

We're not getting overrun by millions of immigrants.

JUDY WOODRUFF: That's not how Polo sees it.

RAFAEL POLO: I think they need to come in legally.

A lot of the folks that are coming through, a lot of them are not good people.

They're rapists, murderers.

And I'm pretty convinced that terrorists are here.

JUDY WOODRUFF: When it comes to former President Trump, who famously launched his campaign by denigrating Mexicans... DONALD TRUMP, Former President of the United States (R) and Current U.S. Presidential Candidate: They are bringing drugs, they are bringing crime.

They are rapists.

And some, I assume, are good people.

JUDY WOODRUFF: ... and has repeatedly disparaged immigrants as he calls for more restrictive policies... SYLVIA GONZALEZ ANDERSH: His first comment was that all Mexicans are rapists and murderers.

Well, what, I supposed to open and -- have open arms?

That's not true.

My family is nothing like that, and most immigrants are nothing like that.

I'm not going to stand by and let them say Mexicans are terrible or Latinos are terrible.

That's -- that's not acceptable.

That is not American.

RAFAEL POLO: You know, I'm from New York, so I grew up with people like Donald.

So it doesn't bother me.

JUDY WOODRUFF: And do you think he'd be a good president again?

RAFAEL POLO: I think he'd be outstanding.

JUDY WOODRUFF: That division reflects one playing out across the country.

And while Latinos have long been a key constituency of the Democrats, recent polling shows that the gap between the parties is tightening, with 44 percent of registered Latino voters favoring Donald Trump and 52 percent supporting Joe Biden.

SAMARA KLAR, Professor, University of Arizona School of Government and Public Policy: The Latino community is so diverse that we want to look at every group really based on their country of origin, more than anything else.

JUDY WOODRUFF: Samara Klar is a professor at the School of Government and Public Policy at the University of Arizona.

She tells us these differences of opinion should not come as a surprise.

SAMARA KLAR: To say how do Cubans compare with Mexicans is almost saying, like, how do Canadians compare with Japanese immigrants?

I mean, these are two completely different countries, people who come here at different times under different circumstances.

JUDY WOODRUFF: She studies how an individual's personal identities and social surroundings influence their political attitudes and behaviors, and says, because of common experiences among Latinos, she sees less partisan hostility.

SAMARA KLAR: So, for white Democrats and white Republicans, there's not a lot that really bonds them.

For Latino Democrats and Latino Republicans, we see linguistic ties.

We see religious ties.

We see experiences with discrimination.

We see experiences as a minority or as an immigrant.

JUDY WOODRUFF: So, as you think about Latinos as a voting bloc, what should we think about it?

SAMARA KLAR: Well, first, I would not think about Latinos as a voting bloc.

Latinos are an incredibly diverse community of people.

We have Latinos who come from dozens of countries all over the world,different nationalities, different backgrounds, different histories, different immigration patterns, different immigration eras.

It can be a little confusing, because it makes it harder to understand voting patterns within this very diverse group of people.

JUDY WOODRUFF: At the same time, the sheer size of the Latino community hasn't always translated into political power or representation.

MARIE ARANA, Author, "LatinoLand: A Portrait of America's Largest and Least Understood Minority": We're very often not made to feel that we fit in.

We're not in the schoolbooks.

We're not in the textbooks.

So this is really wonderful representation because... JUDY WOODRUFF: Marie Arana is an award-winning author, journalist, and the former inaugural literary director at the Library of Congress, where we met.

In her new book, "LatinoLand," Arana she has taken on an admittedly difficult task by attempting to cover 500 years of Latino history in the United States.

MARIE ARANA: Even though there are we have a great number, millions of eligible voters, we do not necessarily register to vote.

And that is a problem for us.

That is a real problem.

JUDY WOODRUFF: Where does that come -- stem from?

Where does that come from?

MARIE ARANA: Well, it comes from the fact that you're -- prejudice, discrimination, a sense of not fitting in.

There is this sense that, why should we vote?

We're not paid attention to anyway.

JUDY WOODRUFF: But now she believes that, during this polarized period in our country, a diverse Latino community can help moderate American politics.

MARIE ARANA: There is within the Latino population itself, we represent diversity within -- within us because of the many races that we are.

And I think, in general, we are a moderating force.

JUDY WOODRUFF: Back in Tucson, Professor Klar says her research bears that out, showing a key difference between most Latinos and non-Latino white voters.

SAMARA KLAR: We find that, for Latinos in Arizona and elsewhere across the country, they express much warmer feelings toward the other party.

Their feelings toward their own party are about the same.

So it's not like they're cheerleaders for every party.

But there's much less affective polarization or personal dislike between the parties within the Latino community.

JUDY WOODRUFF: And what is this over here on the left, upper left?

2020?

RAFAEL POLO: Yes.

JUDY WOODRUFF: That is true Raf Polo.

He says he hasn't let politics get in the way of his relationships.

Can you talk to your friends who are Democrats about issues?

RAFAEL POLO: Yes.

Yes.

We're all educated.

We're experienced, successful people that don't need to use short words to express themselves.

JUDY WOODRUFF: You haven't built a wall between your house and a neighbor who's a Democrat or a liberal or something?

RAFAEL POLO: No.

No, no, no.

It's -- God, we have got a bunch of liberal -- liberals right down the street.

(LAUGHTER) JUDY WOODRUFF: But Sylvia Gonzalez Andersh prefers to steer clear of politics with her Republican neighbors.

She told us she has family members who support former President Trump, and that she struggles with the fact that other Latinos have a more negative view than she has toward new immigrants.

SYLVIA GONZALEZ ANDERSH: Well, I could get really dark about that.

I could really think, well, if you are willing to do -- to turn against your own people and pull up the ladder behind you, that means that you have the same traits as, you know, somebody that just wants to get ahead at any cost.

It's just a lack of empathy, a lack of -- I got mine and you don't - - I don't care if you get yours.

JUDY WOODRUFF: It's anyone's guess how this will break in such a hard-fought election year, but what is clear is that both campaigns will be making their case to the 36.2 million eligible Latino voters.

For the "PBS NewsHour," I'm Judy Woodruff in Tucson, Arizona.