If you've got a smartphone, you've probably got that app you can't live without. Maybe it's a game, or maybe it tells you the weather.

A growing number of Ted Cruz supporters are checking their smartphones every day, in an effort to gain points and make their way to the top of the "Cruz's Crew" leaderboard.

The Texas senator's campaign is hoping that the app — and the competition it fosters — will motivate voters to not only volunteer and contribute to their effort, but also turn over a lot of vital personal information.

The app, designed by UCampaign, isn't too flashy. It provides news about Cruz, as well as a calendar highlighting upcoming events.

The heart of the app, though, prompts users to acquire points by taking a variety of actions: post pro-Cruz messages to Facebook or Twitter, donate money and sign up to volunteer.

"The idea was to gamify campaign activities," explains Chris Wilson, Cruz's director of research and analytics. "That's kind of a new word that means create games and challenges around doing things that have always driven a political campaign."

But in addition to prompting supporters to broadcast their support for Cruz, the app also attempts to gather information about people's social networks and friend groups.

Whenever a new user logs in, the app asks for access to their phone's contact list. Turning over that information earns a user 250 points. By comparison, a contribution only gets 10 points.

"While we don't keep anything that they share, what it does allow us to do is identify within a person's contact list, those voters that may be part of our core targeting list," Wilson says.

The campaign is searching for information — names, address, phone numbers — that match up with possible Cruz voters. "We have scored the entire national voter file, in terms of their likelihood to support Ted Cruz," Wilson says. "So if we identify that you have 10 friends in Iowa who are potential Cruz supporters, then we'll ask you to reach out to those people."

The app looks for other personal information, too. It asks users to sign different petitions, to get a sense of what issues motivate them. It asks for a user's name, email address, phone number, ZIP code, gender and age range, among other details.

There's a limit to how successful these attempts can be. Just think about your own contact list and how many people are in there under nicknames. "Mom" and "Dad" probably don't go too far in helping a campaign lock in on potential voters.

There's also the matter of reach. More than 20,000 people have downloaded the app, but Cruz doesn't tell people about it during his powerful campaign stump speech.

Still, the app is motivating a growing number of Cruz supporters.

"Being for the most part retired, I am on social media every day," explains Kay Quirk, who works as Cruz's campaign chair in Buena Vista County, Iowa. She said the Cruz app is now up there with Facebook and Twitter when it comes to her daily social media use. "I go on there every single day. That's why I've garnered so many points."

And she has. Quirk has amassed nearly 70,000 points on the app. Her closest competition in Iowa is a man named Edward, who has fewer than 15,000.

Most of Quirk's points come from sharing messages on Twitter and Facebook. Shortly before speaking to NPR, she had posted a meme-type image of Cruz and former Arkansas Gov. Mike Huckabee, reminding her friends that the Republican candidates would hold another debate that night.

"If people like that, then I get more points on my Cruz Crew app. I get 5 points for every like I get," she explains.

The only rewards top point-earners get are shoutouts on Cruz's social media accounts. That's recognition enough for Quirk and other Cruz fans.

"It's just one more avenue of getting the word out," says Linda Stickle, another Cruz volunteer and the Jones County campaign chair. "Getting a picture — whatever it takes."

For the Cruz campaign, it's one more avenue to tap into the trove of voter information that helps build the databases and voter models that drive modern campaigns.

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