AUDIE CORNISH, HOST:
Hillary Clinton has broken a political glass ceiling. She's now officially the first woman presidential nominee of a major political party. Delegates at the DNC in Philadelphia approved Clinton's nomination by acclamation tonight after a motion from her primary rival, Bernie Sanders.
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BERNIE SANDERS: I move that Hillary Clinton be selected as the nominee of the Democratic Party for president of the United States.
CORNISH: NPR's Scott Horsley was on the convention floor. He's now at my side. Scott, help us understand how this roll call process went.
SCOTT HORSLEY, BYLINE: Audie, this was a classic roll call with each state using its moment in the spotlight to offer some local color and tout some hometown heroes. And the Clinton campaign felt it was important to get all the way through that process, so there was no big celebration when Clinton actually crossed the threshold of votes needed to secure the nomination.
Instead they let every delegate in every state be counted, and then they circled back to Vermont which had passed during the initial roll call. And once Vermont's delegate totals were announced, Bernie Sanders, the senator from Vermont, stood up and moved to Hillary Clinton be nominated by acclimation, a move that was loudly approved here on the convention floor. So we got a nod to party unity, but we also let every Clinton and every Sanders vote be counted.
CORNISH: Now, later tonight we're going to hear from former President Bill Clinton. What's he going to do to make the case for his wife?
HORSLEY: Well, Bill Clinton has always had a lot of star power at Democratic conventions. Four years ago he made one of the most persuasive arguments for Barack Obama's re-election at the Charlotte Convention. In fact, President Obama later joked about a kid who'd recommended he make Clinton - Bill Clinton the Secretary of Explaining Stuff. Bill Clinton's job tonight is to explain who Hillary Clinton is and how she got to this point.
CORNISH: Can you talk about some of the other speakers tonight. I know that we've got a segment kind of coming up on criminal justice.
HORSLEY: That's right. We're going to be hearing from some folks who've been victims of police violence. We're hearing right now from Attorney General Eric - former Attorney General Eric Holder. And so it's a big program still ahead. Right now there's actually a lot of empty seats in the arena. A number of people left the arena right after the roll call, some of them to head for the food court or the restrooms, and some, though, were angry Bernie Sanders supporters who walked out in protest. We understand...
CORNISH: And walked right to the media tent.
HORSLEY: There are now several hundred holding court in the media tent. It's going to be interesting to see when the primetime program gets into full swing how many of these seats will fill back up.
CORNISH: Meanwhile the nominee herself - (laughter) where did she watch this - tonight's roll call?
HORSLEY: Hillary Clinton watched tonight from her home in Chappaqua, N.Y. She will be back of course formally accepting the nomination here on Thursday night. And then on Friday, she and her new running mate, Tim Kaine, are embarking on a bus tour, sort of an old school bus tour through Pennsylvania and Ohio.
CORNISH: And that's NPR's Scott Horsley's. Scott, thank you.
HORSLEY: Good to be with you, Audie. Transcript provided by NPR, Copyright NPR.