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Like all campaigns competing in Iowa and New Hampshire, the former vice president's team is now putting more energy into its ground game in those states, knocking on doors, hoping to convince undecided voters. NPR's Scott Detrow spent some time this past week with the Biden campaign in New Hampshire.
SCOTT DETROW, BYLINE: A month before the primary, this is one of the most important sounds a campaign can hear...
(SOUNDBITE OF FOOTSTEPS)
DETROW: ...The footsteps of campaign organizers and volunteers out in the cold, knocking on doors. The windchill is 7 degrees, but Cari Berlin isn't wearing a hat, and her coat is unzipped.
CARI BERLIN: I'm very hot-natured. Yeah. So I like the cold (laughter).
DETROW: Berlin is from Arkansas, but she's adapted to the New Hampshire cold since joining the Biden campaign this summer.
UNIDENTIFIED PERSON: Come on in out of the cold.
BERLIN: OK. We'll stand right at the front.
UNIDENTIFIED PERSON: Right.
DETROW: Berlin guesses she's knocked on thousands of doors. For all the high-tech ways campaigns reach voters - texts, emails, targeted ads - this old-school tool is still important.
BERLIN: Oh, door knocking is definitely the most valuable. It's a face-to-face interaction. And you actually get the chance to listen to the issues that people care about and then to be able to...
DETROW: The Biden organizer finds luck in one of the first houses she hits.
JOHN DAY: He is what I would vote on just about everything, I believe.
DETROW: In fact, John Day (ph) has already voted for Biden absentee since he'll be out of the state during the primary. Still, Berlin asks him to sign a commit-to-vote postcard.
DAY: You want the rest of the stuff there, too?
BERLIN: You don't have to put in the email and the phone, but if you could do the day and then just print your first name, I'd...
DETROW: The campaign tracks voters with these and what issues they care about. They also mail the postcards back. Political science research shows that just being reminded you made a promise to someone can motivate a voter to go to the polls.
BERLIN: So now I think we're going to 1250.
DETROW: Door knocking maybe the most valuable tool, but it has its downsides.
BERLIN: Looks like they were not home.
DETROW: Each day is different. Sometimes you get a lot of voters at home, sometimes not. Berlin says over the months, she's learned some best practices. Wait a little longer at the door in case people are busy.
BERLIN: So I also like to step back away from the front door. And that's people's comfort zones and their kind of personal area. I like to kind of go to, like, the third step so that when they come out, I'm not just right there (laughter) as a stranger.
DETROW: The campaign mostly targets Democrats, but independents can vote in the New Hampshire primary, too. So sometimes Berlin has moments like this.
BERLIN: All right. Do you - have you decided where you're leaning?
AMY BARREN: Probably Trump.
BERLIN: Probably Trump.
DETROW: Still, Amy Barren (ph) says she could see herself voting Biden.
BARREN: I mean, he's been around for a while. I mean, the whole touchy-feely thing doesn't bother me (laughter).
DETROW: The morning goes on - no more Trump voters, a lot more no-shows, then more success.
BERLIN: Yeah, two more Joe votes. It's exciting (laughter)
DETROW: One trademark of this race is the amount of Democrats who haven't made up their minds. Berlin says she sees that number getting smaller.
Scott Detrow, NPR News, Manchester. Transcript provided by NPR, Copyright NPR.