KELLY MCEVERS, HOST:
As this Democratic primary winds down and the Republican nomination is all but secured by Donald Trump, we are starting to see a lot of general election polls. A whole round of polls came out this weekend, and they show a presidential race that is rapidly tightening. Or is it?
We are joined now by NPR's Danielle Kurtzleben and Domenico Montanaro to help us make sense of these poll numbers and tell us what we should and shouldn't be paying attention to. Welcome to you both.
DANIELLE KURTZLEBEN, BYLINE: Thank you. Hello.
DOMENICO MONTANARO, BYLINE: Good to be with you.
MCEVERS: To start, how seriously should we be taking these polls?
KURTZLEBEN: Well, the answer to that is that polls are a snapshot. They show you how things are, but they show you how they are right now. And that's important. Polls are to be believed, but they're not predictive of election day. So what I mean by that is that Hillary Clinton and Donald Trump are in very different places right now.
Donald Trump has defeated all of the other Republicans who were in the contest while Clinton is still fighting a two-front battle. She is finishing her nomination contest against Bernie Sanders, but she's also running against Donald Trump at the same time. So that's just one factor that could be weighing on her numbers.
That said, there's still useful information in these polls. You just have to look a bit deeper behind the horse race numbers.
MCEVERS: So if you don't look at the horse race numbers, what number are you looking at?
KURTZLEBEN: I mean, I would say two things. One is the favorability and unfavorability numbers. The NBC Wall Street Journal poll that came out this weekend showed that these two would be the most unpopular nominees in the history of that poll. So Clinton and Trump really have some problems there.
The other thing to look at is demographics. It shows you who is doing well with whom. Clinton does well with women. She does well with minorities. Trump does well with white people and men.
MONTANARO: I think it's also important to look at issues and personal characteristics. I mean, when you look at the ABC Washington Post poll, for example, when you ask people, who's qualified to be president, 63 percent said Hillary Clinton is most qualified, and Donald Trump - only 39 percent said that he was qualified. Almost the reverse - 58 percent - said he was not qualified to be president.
When you look at attributes, experience, temperament, realistic policies, understands your problems - all of those were things that Hillary Clinton scores very well on. So a lot of these polls underneath those horse race numbers can tell you a little bit something about things that are maybe less volatile and a bit more stable in people's understanding of these candidates.
MCEVERS: We just heard a report on how committed Bernie Sanders' supporters are and what a negative view they have of Clinton. How might that affect Hillary Clinton in a general election race?
MONTANARO: Clearly in the NBC News Wall Street Journal poll you could see that Hillary Clinton - only up three in the top line number after being ahead - much wider margins for quite some time. What's really changed here is that Bernie Sanders' supporters are holding out their support. Over 80 percent of Democrats, for example, say that they back Clinton, but only 66 percent of Sanders' supports are saying they will.
That's kind of similar to what you saw in 2008 where Hillary Clinton's supporters - only about 60 percent said that they would go to Barack Obama. The difference here, though, is that more Sanders people seem to not like Hillary Clinton than Clinton folks liked Barack Obama.
KURTZLEBEN: Right, and one thing you might be seeing on the Republican side, on the flipside, is this sort of rallying effect around the party nominee. Donald Trump has secured his party's nomination much more quickly than anyone on the Democrat side is. Clinton still looks like the likely nominee over there, but she still hasn't wrapped it up yet. So that may be boosting Trump's figures right now.
MCEVERS: Even though the delegate math is decidedly against Bernie Sanders at this point, his campaign says he should be the nominee because he's polling better against Donald Trump than Hillary Clinton is in the general election. And these polls do show him ahead, right?
MONTANARO: They do - but big caveat here, though, is that you haven't seen a lot of scrutiny against Bernie Sanders. Think about his tax plan. The Tax Policy Center came out and said it would cost $18 trillion, for example. You haven't seen any negative ads against him on for precisely the reason that delegate math is decidedly against him.
So there's a big difference here between how someone is viewed when they're viewed as the person who's going to be the nominee and when they're not.
KURTZLEBEN: Right, and to add in there - it just hasn't served Clinton or Trump to really attack Sanders yet. Clinton wants his supporters eventually, and Donald Trump has an interest in boosting him to prolong the Democratic race.
MONTANARO: And the bottom line here is that the general election hasn't been litigated yet, and we're nearly six out. And you should really take all of these polls with a grain of salt.
MCEVERS: That's NPR's Domenico Montanaro and Danielle Kurtzleben. Thanks to both of you.
KURTZLEBEN: Thank you.
MONTANARO: Thank you. Transcript provided by NPR, Copyright NPR.