Conservative strategist Steve Bannon oversaw Cambridge Analytica's early efforts to collect troves of Facebook data as part of an ambitious program to build detailed profiles of millions of American voters, a former employee of the data-science firm said Tuesday.
The 2014 effort was part of a high-tech form of voter persuasion touted by the company, which under Bannon identified and tested the power of anti-establishment messages that later would emerge as central themes in President Donald Trump's campaign speeches, according to Chris Wylie, who left the company at the end of that year.