WASHINGTON (AP): Republican presidential candidate Ted Cruz has campaigned against government spying on law-abiding citizens, but his campaign is testing the limits with personal data from his supporters.

His “Cruz Crew” mobile app is designed to gather detailed information from users’ phones tracking their physical movements and mining contact information of friends.

That information is fed into a database containing details about nearly every adult in the U.S. to build psychological profiles that target individual voters with uncanny accuracy.

Data-mining to help candidates win elections has been increasingly used by both Republicans and Democrats. But The Associated Press found the Cruz campaign’s app goes furthest to glean personal data. It’s been downloaded to more than 61,000 devices so far.