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Three days after the election, Vice President Joe Biden has a slight lead in Pennsylvania and Georgia. A win for Biden in either of those states would see him win the Electoral College and the presidency. But that's not the whole story. For more, we're going to hear from Domenico Montanaro.

Domenico, welcome back.

DOMENICO MONTANARO, BYLINE: Hey there.

CORNISH: Let's start with Georgia. What is the latest on what's happening there?

MONTANARO: Well, the latest in Georgia is that Joe Biden actually picked up a couple thousand votes since we last talked. He's at now about - a lead of about 4,100 votes. And, you know, there are still thousands of ballots out - not many, probably within about 10,000 - as well as provisional ballots that haven't been counted yet. And those provisionals may very well increase Biden's lead. And what's important about that is that in a recount situation, which is where this is likely headed, it's very difficult to overturn a margin where you've got thousands and thousands of votes as opposed to a few hundred.

CORNISH: There's also a lot of scrutiny of Pennsylvania. What is the tally there as of now?

MONTANARO: Well, we've been getting some new numbers in Pennsylvania just in the last hour, and Joe Biden's lead is up to now almost 20,000. Allegheny County, where Pittsburgh is, there were 5,300 ballots and 4,100 of them went for Biden and just about a thousand for Trump. So you see there he's been pulling about 80% in Allegheny County, about 70% in the rest of the state for these mail-in ballots. And that trend is continuing.

One thing to watch is the margin and whether or not Joe Biden gets above or when he gets above 35,000, 36,000 or so because that is going to be outside the margin that triggers an automatic recount, which is what I think a lot of the TV networks are waiting for to make a call there to be sure. And just by my math, what's left in Philadelphia - about 23,000 votes - Biden, if he continues along the lines of what he's been getting, should net roughly 14- or 15,000 out of there. And that could very well do it. And that would still be 75,000 votes left to count in the rest of the state.

CORNISH: Now, two states in which both candidates seem to be very much in the lead - North Carolina and Nevada. Can you talk about which way they're leaning and what you're hearing now?

MONTANARO: North Carolina is leaning toward President Trump. They're finally starting to count some ballots there. And President Trump today picked up, you know, about 400 more votes in the last hour. And he's at about 77,000 lead. Both campaigns expect that that will go to President Trump when all the counting is done. And Nevada, the lead is expanding there for Joe Biden. It's up to about almost 23,000 now because the ballots that are coming in are from Clark County. We're probably not going to see all the vote there, so I doubt that we'll see a call in Nevada tonight.

CORNISH: Speaking of calls, The Associated Press - which of course, NPR relies on for our calls - and Fox News have both called Arizona for Biden. There are some news organizations that have not. So I know that has been confusing to some people out there seeing the different counts. Any update on Arizona?

MONTANARO: Yeah, that's right. You know, we rely on the AP for their calls, but we also watch the vote closely, as does the AP. You know, if the margin got within an area where they felt like they needed to retract their call, they would do so. Right now it continues to shrink, and Donald Trump is within 3,800 - 38,000 votes - sorry - of Joe Biden in Arizona. But, you know, he's going to need, for what's left there, you know, something like mid- to high-50% margin to be able to pull off that many ballots. Democrats don't think he'll be able to and that, at the end of the day, Biden will wind up winning in Arizona. But we're going to have to watch the count.

CORNISH: While we're all waiting for a final answer to the question of who's won the Electoral College, what are you going to be watching for the next few hours?

MONTANARO: Well, the next few hours in particular - Pennsylvania, because if that, you know, is able to be called, then that would do it. We wouldn't have to think about any of the other states because Joe Biden, even without Arizona, would have enough to go over 270 and be declared president-elect.

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

Thanks for the update.

MONTANARO: Yeah, you're welcome. Transcript provided by NPR, Copyright NPR.