Archbishop John J. Myers stands outside Cathedral Basilica of the Sacred Heart in Newark, N.J. The archbishop has urged followers to assess the presidential candidates for their views on abortion and gay marriage.

GUY RAZ, HOST:

It's WEEKENDS on ALL THINGS CONSIDERED from NPR News. I'm Guy Raz.

We just heard about the pivotal role Ohio will likely play in determining who will end up winning the White House, but both President Obama and Governor Mitt Romney would also do well winning another bellwether group: Catholics. Since 1972, every single presidential candidate who has won the popular vote has also won the Catholic vote. One in four voters are Catholics. Now, historically, they voted for Democrats. And the reason? Here's pollster Robert Jones with the Public Religion Institute.

DR. ROBERT JONES: Part of it really is this alignment between the labor union movement and Catholics, who were really, up until the '70s, still really concentrated in Catholic enclaves in bigger cities, still working class...

RAZ: The rustbelt areas like that.

JONES: That's right, rust belt. They were just beginning to be the rust belt at that time. That's exactly right. And so I think it's this kind of interlocking between labor, the Democratic Party and a Catholic base that we really see really intact all the way up through the late 1960s.

RAZ: So 1972 is the turning point. It's - Richard Nixon, of course, wins the popular vote and more Catholics go with Richard Nixon rather than George McGovern.

JONES: That's right.

RAZ: So what happens in 1972? What suggests the shift?

JONES: You know, I think it's a combination of things. What we really see is sort of a gradual movement. I mean, 1968, you know, it was 59 percent voted for the Democratic candidate in 1968 versus, you know, nearly eight in 10 in Kennedy. So we had begun to see kind of a slide. But it's not really till 1972 that we really see this division with Catholics really going Republican or Democrat depending on the election and looking really like the bellwether constituency that really goes with the general population.

What's behind that, I think, really is 100 years of integration. So we have the biggest wave of Catholic immigration in the late 19th century and then we have several generations. By the time we get to 1972, we have nearly a century of Catholic integration with Catholics having upward mobility in terms of education, in terms of income. And I think, importantly, moving out of Catholic enclaves in larger cities like New York and Chicago.

RAZ: Let's talk about now. We still hear this notion of a Catholic voting bloc. But there is no Catholic voting bloc.

JONES: I think that's right. I mean, one thing to say is that this is a really large group of voters, and they make up a quarter of all American voters. But I would say there are at least two Catholic votes in the country, and they divide pretty cleanly by ethnicity. So white, non-Hispanic Catholics, for example, in the last election supported John McCain over Barack Obama. However, if you look at the Latino Catholic vote, nearly three quarters of the Latino Catholic vote supported President Barack Obama.

RAZ: Which meant that Obama got more Catholic votes in total.

JONES: That's right. But it was the Latino Catholic vote that put Obama over the top...

RAZ: That put him over.

JONES: ...because the white Catholic vote actually went slightly for John McCain.

RAZ: So which reflects the white vote in general, which tends to favor the Republican over the Democrat. How do campaigns appeal to Catholic voters? I mean, you've got - let's say, for example, you've got the Joe Biden Catholics and then you've got the Paul Ryan Catholics, two really distinctive wings of the faith.

JONES: Well, I think one thing's important is to understand that the official position of the Catholic Church is not necessarily the official position of Catholic voters. So just to give you a couple of examples. Whereas the Catholic Church has a strong position against contraception, the overwhelming majority of Catholics say that they have no moral problems with birth control or contraception.

Catholics are basically divided on the issue of abortion overall, and a majority of Catholics actually support allowing gay and lesbian couples to marry, which is very different than, of course, the official Catholic Church position. So if you're, you know, a Republican Party operative or a Democratic Party operative, it's a little bit complicated of how exactly to reach out to Catholic voters who have a very complex set of values. It doesn't always line up with the official positions of the Catholic Church.

RAZ: Robert Jones is with the Public Religion Institute. To get a better sense of those complex set of values he was talking about, we asked Catholic voters in two battleground states - Wisconsin and Pennsylvania - what matters most to them in this election. Everyone we asked at St. Francis Borgia Church in the town of Cedarburg, just outside Milwaukee, everyone we asked said they'll be backing...

UNIDENTIFIED MAN #1: Romney.

UNIDENTIFIED MAN #2: Romney.

UNIDENTIFIED MAN #3: Hands down, no question.

UNIDENTIFIED WOMAN #1: I'll be voting for Mitt Romney.

UNIDENTIFIED MAN #4: Because I appreciate a man running for office who can stand up and acclaim God. And he did it a number of times in his speech at the convention, and that's all important to us as Catholics.

UNIDENTIFIED MAN #5: It's certainly the Republican Party at present is standing up for those things that we believe in, which is no abortion, for one thing. Flat out.

UNIDENTIFIED WOMAN #2: Well, I think the Catholicism, you know, you read the Bible, you go to church, I mean, certainly some of these issues are present in a mass, and typically Catholic people are a little bit more conservative.

RAZ: That was Tom Conlin(ph), Gary Peterson(ph) and Michele Fitzpatrick(ph), all worshippers at St. Francis Borgia Church in Cedarburg, Wisconsin. Now, we found a very different set of Catholic voters 1,000 miles away at Visitation of the Blessed Virgin Mary parish in Philadelphia.

UNIDENTIFIED WOMAN #3: So far, I'm going for and I'm thinking of Obama.

UNIDENTIFIED WOMAN #4: Obama.

UNIDENTIFIED WOMAN #5: Obama.

UNIDENTIFIED WOMAN #6: Well, there is a couple of goals that he set, you know, for us Hispanic as in making better education and the economy to make more jobs.

UNIDENTIFIED WOMAN #7: I believe in no abortions. I believe in that, but there's different situations a lot of people do what they do. So, you know, who am I to judge?

UNIDENTIFIED WOMAN #8: I just think Obama cares more for, like, people who don't have means.

RAZ: The voices of Leslie Rodriguez(ph), Maribel Romero(ph) and Desiree Santano(ph), who we spoke to outside Visitation of the Blessed Virgin Mary parish in Philadelphia.

The latest Pew poll, by the way, has President Obama up 15 points over Mitt Romney with all Catholic voters. That's up from a two-point lead he had in June. And while the two candidates are tied among white Catholics, President Obama gets a big boost from Latino Catholics. Transcript provided by NPR, Copyright NPR.