The Ted Cruz campaign has quietly stopped using a new “behavioral” voter targeting technology from Cambridge Analytica, which has been called both “the new kid on the block” in campaign tech and Cruz’s “secret weapon,” according to sources with knowledge of the matter.

The Cruz campaign had been using the Cambridge Analytica data, technology, and some of its people since mid-2015. But two well-placed sources tell Fast Company that after testing the data and technology, it’s been abandoned in favor of older but more battle-hardened targeting methods.

The Cruz campaign, however, continues to employ four Cambridge Analytica data scientists. “We cannot comment on any existing clients, and we don’t comment on rumors,” a Cambridge Analytica spokesman told Fast Company.

The experiment proved to be an expensive one for the Cruz camp, which, according to FEC filings, has paid out at least $3.8 million to Cambridge Analytica during the campaign.

The British company has its roots in military “psy-ops” research, and only arrived on the U.S. political data analytics scene in 2014.

The company provides a method of analyzing the personality traits of voters to determine which political messages might move them to action. The company creates personality models based on the “big five” traits known as the OCEAN scale: openness, conscientiousness, extraversion, agreeableness, and neuroticism.

A voter who scores high on the neuroticism and openness scales might be targeted with an ad about the the threat of the government taking their guns away, says one Cambridge Analytica executive.